diff --git a/Makefile.am b/Makefile.am
index e111680..197ab35 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -63,7 +63,8 @@ bin_iscsi_test_SOURCES = test-tool/iscsi-test.c \
 	test-tool/0132_verify10_mismatch_no_cmp.c \
 	test-tool/0143_read12_rdprotect.c \
 	test-tool/0153_read16_rdprotect.c \
-	test-tool/0160_readcapacity16_simple.c
+	test-tool/0160_readcapacity16_simple.c \
+	test-tool/0170_unmap_simple.c
 endif
 
 # LD_PRELOAD library.
diff --git a/include/iscsi.h b/include/iscsi.h
index 84114ae..a92c595 100644
--- a/include/iscsi.h
+++ b/include/iscsi.h
@@ -613,6 +613,16 @@ iscsi_modesense6_task(struct iscsi_context *iscsi, int lun, int dbd,
 			   unsigned char alloc_len, iscsi_command_cb cb,
 			   void *private_data);
 
+struct unmap_list {
+       uint64_t	  lba;
+       uint32_t	  num;
+};
+
+EXTERN struct scsi_task *
+iscsi_unmap_task(struct iscsi_context *iscsi, int lun, int anchor, int group,
+		 struct unmap_list *list, int list_len,
+		 iscsi_command_cb cb, void *private_data);
+
 
 /*
  * Sync commands for SCSI
@@ -662,6 +672,10 @@ iscsi_verify10_sync(struct iscsi_context *iscsi, int lun,
 		    int vprotect, int dpo, int bytchk, 
 		    int blocksize);
 
+EXTERN struct scsi_task *
+iscsi_unmap_sync(struct iscsi_context *iscsi, int lun, int anchor, int group,
+		 struct unmap_list *list, int list_len);
+
 /*
  * This function is used when  the application wants to specify its own buffers to read the data
  * from the DATA-IN PDUs into.
diff --git a/include/scsi-lowlevel.h b/include/scsi-lowlevel.h
index d1bfb62..043b6cf 100644
--- a/include/scsi-lowlevel.h
+++ b/include/scsi-lowlevel.h
@@ -29,6 +29,7 @@ enum scsi_opcode {
 	SCSI_OPCODE_WRITE10            = 0x2A,
 	SCSI_OPCODE_VERIFY10           = 0x2F,
 	SCSI_OPCODE_SYNCHRONIZECACHE10 = 0x35,
+	SCSI_OPCODE_UNMAP              = 0x42,
 	SCSI_OPCODE_READ16             = 0x88,
 	SCSI_OPCODE_SERVICE_ACTION_IN  = 0x9E,
 	SCSI_OPCODE_REPORTLUNS         = 0xA0,
@@ -561,7 +562,9 @@ EXTERN struct scsi_task *scsi_cdb_synchronizecache10(int lba, int num_blocks,
 			int syncnv, int immed);
 EXTERN struct scsi_task *scsi_cdb_serviceactionin16(enum scsi_service_action_in sa, uint32_t xferlen);
 EXTERN struct scsi_task *scsi_cdb_readcapacity16(void);
+EXTERN struct scsi_task *scsi_cdb_unmap(int anchor, int group, uint16_t xferlen);
 
+void *scsi_malloc(struct scsi_task *task, size_t size);
 
 #endif /* __scsi_lowlevel_h__ */
 
diff --git a/lib/libiscsi.def b/lib/libiscsi.def
index 988fa07..f7de01f 100644
--- a/lib/libiscsi.def
+++ b/lib/libiscsi.def
@@ -91,4 +91,5 @@ scsi_cdb_write10
 scsi_cdb_synchronizecache10
 scsi_cdb_readcapacity16
 scsi_cdb_serviceactionin16
+scsi_cdb_unmap
 
diff --git a/lib/scsi-command.c b/lib/scsi-command.c
index e3e481b..51f6636 100644
--- a/lib/scsi-command.c
+++ b/lib/scsi-command.c
@@ -794,6 +794,53 @@ iscsi_synchronizecache10_task(struct iscsi_context *iscsi, int lun, int lba,
 	return task;
 }
 
+struct scsi_task *
+iscsi_unmap_task(struct iscsi_context *iscsi, int lun, int anchor, int group,
+		 struct unmap_list *list, int list_len,
+		 iscsi_command_cb cb, void *private_data)
+{
+	struct scsi_task *task;
+	struct iscsi_data outdata;
+	unsigned char *data;
+	int xferlen;
+	int i;
+
+	xferlen = 8 + list_len * 16;
+
+	task = scsi_cdb_unmap(anchor, group, xferlen);
+	if (task == NULL) {
+		iscsi_set_error(iscsi, "Out-of-memory: Failed to create "
+				"unmap cdb.");
+		return NULL;
+	}
+
+	data = scsi_malloc(task, xferlen);
+	if (data == NULL) {
+		iscsi_set_error(iscsi, "Out-of-memory: Failed to create "
+				"unmap parameters.");
+		scsi_free_scsi_task(task);
+		return NULL;
+	}
+	*((uint16_t *)&data[0]) = htons(xferlen - 2);
+	*((uint16_t *)&data[2]) = htons(xferlen - 8);
+	for (i = 0; i < list_len; i++) {
+		*((uint32_t *)&data[8 + 16 * i])     = htonl(list[0].lba >> 32);
+		*((uint32_t *)&data[8 + 16 * i + 4]) = htonl(list[0].lba & 0xffffffff);
+		*((uint32_t *)&data[8 + 16 * i + 8]) = htonl(list[0].num);
+	}
+
+	outdata.data = data;
+	outdata.size = xferlen;
+
+	if (iscsi_scsi_command_async(iscsi, lun, task, cb, &outdata,
+				       private_data) != 0) {
+		scsi_free_scsi_task(task);
+		return NULL;
+	}
+
+	return task;
+}
+
 unsigned char *
 iscsi_get_user_in_buffer(struct iscsi_context *iscsi, struct iscsi_in_pdu *in, uint32_t pos, ssize_t *count)
 {
diff --git a/lib/scsi-lowlevel.c b/lib/scsi-lowlevel.c
index b2eb435..4ea7dcb 100644
--- a/lib/scsi-lowlevel.c
+++ b/lib/scsi-lowlevel.c
@@ -55,7 +55,7 @@ scsi_free_scsi_task(struct scsi_task *task)
 	free(task);
 }
 
-static void *
+void *
 scsi_malloc(struct scsi_task *task, size_t size)
 {
 	struct scsi_allocated_memory *mem;
@@ -759,6 +759,36 @@ scsi_cdb_verify10(uint32_t lba, uint32_t xferlen, int vprotect, int dpo, int byt
 }
 
 
+/*
+ * UNMAP
+ */
+struct scsi_task *
+scsi_cdb_unmap(int anchor, int group, uint16_t xferlen)
+{
+	struct scsi_task *task;
+
+	task = malloc(sizeof(struct scsi_task));
+	if (task == NULL) {
+		return NULL;
+	}
+
+	memset(task, 0, sizeof(struct scsi_task));
+	task->cdb[0]   = SCSI_OPCODE_UNMAP;
+
+	if (anchor) {
+		task->cdb[1] |= 0x01;
+	}
+	task->cdb[6] |= group & 0x1f;
+
+	*(uint16_t *)&task->cdb[7] = htons(xferlen);
+
+	task->cdb_size = 10;
+	task->xfer_dir = SCSI_XFER_WRITE;
+	task->expxferlen = xferlen;
+
+	return task;
+}
+
 /*
  * MODESENSE6
  */
diff --git a/lib/sync.c b/lib/sync.c
index 352094d..6b9e876 100644
--- a/lib/sync.c
+++ b/lib/sync.c
@@ -361,6 +361,26 @@ iscsi_verify10_sync(struct iscsi_context *iscsi, int lun, unsigned char *data, u
 	return state.task;
 }
 
+struct scsi_task *
+iscsi_unmap_sync(struct iscsi_context *iscsi, int lun, int anchor, int group,
+		 struct unmap_list *list, int list_len)
+{
+	struct iscsi_sync_state state;
+
+	memset(&state, 0, sizeof(state));
+
+	if (iscsi_unmap_task(iscsi, lun, anchor, group, list, list_len,
+				       scsi_sync_cb, &state) == NULL) {
+		iscsi_set_error(iscsi,
+				"Failed to send UNMAP command");
+		return NULL;
+	}
+
+	event_loop(iscsi, &state);
+
+	return state.task;
+}
+
 struct scsi_task *
 iscsi_scsi_command_sync(struct iscsi_context *iscsi, int lun,
 			struct scsi_task *task, struct iscsi_data *data)
diff --git a/test-tool/0170_unmap_simple.c b/test-tool/0170_unmap_simple.c
new file mode 100644
index 0000000..b9cc0ae
--- /dev/null
+++ b/test-tool/0170_unmap_simple.c
@@ -0,0 +1,134 @@
+/* 
+   Copyright (C) 2012 by Ronnie Sahlberg <ronniesahlberg@gmail.com>
+   
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 2 of the License, or
+   (at your option) any later version.
+   
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+   
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include <stdio.h>
+#include "iscsi.h"
+#include "scsi-lowlevel.h"
+#include "iscsi-test.h"
+
+int T0170_unmap_simple(const char *initiator, const char *url)
+{ 
+	struct iscsi_context *iscsi;
+	struct scsi_task *task;
+	struct scsi_readcapacity16 *rc16;
+	int ret, i, lun;
+	uint32_t block_size, num_blocks;
+
+	iscsi = iscsi_context_login(initiator, url, &lun);
+	if (iscsi == NULL) {
+		printf("Failed to login to target\n");
+		return -1;
+	}
+
+	/* find the size of the LUN */
+	task = iscsi_readcapacity16_sync(iscsi, lun);
+	if (task == NULL) {
+		printf("Failed to send readcapacity16 command: %s\n", iscsi_get_error(iscsi));
+		ret = -1;
+		goto finished;
+	}
+	if (task->status != SCSI_STATUS_GOOD) {
+		printf("Readcapacity command: failed with sense. %s\n", iscsi_get_error(iscsi));
+		ret = -1;
+		scsi_free_scsi_task(task);
+		goto finished;
+	}
+	rc16 = scsi_datain_unmarshall(task);
+	if (rc16 == NULL) {
+		printf("failed to unmarshall readcapacity16 data. %s\n", iscsi_get_error(iscsi));
+		ret = -1;
+		scsi_free_scsi_task(task);
+		goto finished;
+	}
+
+	if (rc16->lbpme == 0){
+		printf("Logical unit is fully provisioned. Skipping test\n");
+		ret = -1;
+		scsi_free_scsi_task(task);
+		goto finished;
+	}
+
+	block_size = rc16->block_length;
+	num_blocks = rc16->returned_lba;
+
+	scsi_free_scsi_task(task);
+
+	if (!data_loss) {
+		printf("data_loss flag is not set. Skipping test\n");
+		ret = -1;
+		goto finished;
+	}
+	
+	ret = 0;
+
+	/* unmap the first 1 - 256 blocks at the start of the LUN */
+	printf("Unmapping first 1-256 blocks ... ");
+	for (i=1; i<=256; i++) {
+		struct unmap_list list[1];
+
+		list[0].lba = 0;
+		list[0].num = i;
+		task = iscsi_unmap_sync(iscsi, lun, 0, 0, &list[0], 1);
+		if (task == NULL) {
+		        printf("[FAILED]\n");
+			printf("Failed to send UNMAP command: %s\n", iscsi_get_error(iscsi));
+			ret = -1;
+			goto finished;
+		}
+		if (task->status != SCSI_STATUS_GOOD) {
+		        printf("[FAILED]\n");
+			printf("UNMAP command: failed with sense. %s\n", iscsi_get_error(iscsi));
+			ret = -1;
+			scsi_free_scsi_task(task);
+			goto finished;
+		}
+		scsi_free_scsi_task(task);
+	}
+	printf("[OK]\n");
+
+
+	/* unmap the last 1 - 256 blocks at the end of the LUN */
+	printf("Unmapping last 1-256 blocks ... ");
+	for (i=1; i<=256; i++) {
+		struct unmap_list list[1];
+
+		list[0].lba = num_blocks + 1 - i;
+		list[0].num = i;
+		task = iscsi_unmap_sync(iscsi, lun, 0, 0, &list[0], 1);
+		if (task == NULL) {
+		        printf("[FAILED]\n");
+			printf("Failed to send UNMAP command: %s\n", iscsi_get_error(iscsi));
+			ret = -1;
+			goto finished;
+		}
+		if (task->status != SCSI_STATUS_GOOD) {
+		        printf("[FAILED]\n");
+			printf("UNMAP command: failed with sense. %s\n", iscsi_get_error(iscsi));
+			ret = -1;
+			scsi_free_scsi_task(task);
+			goto finished;
+		}
+		scsi_free_scsi_task(task);
+	}
+	printf("[OK]\n");
+
+
+finished:
+	iscsi_logout_sync(iscsi);
+	iscsi_destroy_context(iscsi);
+	return ret;
+}
diff --git a/test-tool/iscsi-test.c b/test-tool/iscsi-test.c
index ed6b1f3..103f131 100644
--- a/test-tool/iscsi-test.c
+++ b/test-tool/iscsi-test.c
@@ -29,6 +29,7 @@
 #include "iscsi-test.h"
 
 const char *initiator = "iqn.2010-11.iscsi-test";
+int data_loss = 0;
 
 struct scsi_test {
        const char *name;
@@ -67,6 +68,9 @@ struct scsi_test tests[] = {
 /* readcapacity16*/
 { "T0160_readcapacity16_simple",	T0160_readcapacity16_simple },
 
+/* unmap*/
+{ "T0170_unmap_simple",			T0170_unmap_simple },
+
 { NULL, NULL }
 };
 
@@ -161,6 +165,7 @@ int main(int argc, const char *argv[])
 		{ "list", 'l', POPT_ARG_NONE, &list_tests, 0, "List all tests", NULL },
 		{ "initiator-name", 'i', POPT_ARG_STRING, &initiator, 0, "Initiatorname to use", "iqn-name" },
 		{ "test", 't', POPT_ARG_STRING, &testname, 0, "Which test to run", "testname" },
+		{ "dataloss", 0, POPT_ARG_NONE, &data_loss, 0, "Allow destructuve tests", NULL },
 		POPT_TABLEEND
 	};
 
diff --git a/test-tool/iscsi-test.h b/test-tool/iscsi-test.h
index 7847f09..72b7c0d 100644
--- a/test-tool/iscsi-test.h
+++ b/test-tool/iscsi-test.h
@@ -18,6 +18,7 @@
 */
 
 struct iscsi_context *iscsi_context_login(const char *initiatorname, const char *url, int *lun);
+extern int data_loss;
 
 
 int T0100_read10_simple(const char *initiator, const char *url);
@@ -43,3 +44,5 @@ int T0143_read12_rdprotect(const char *initiator, const char *url);
 int T0153_read16_rdprotect(const char *initiator, const char *url);
 
 int T0160_readcapacity16_simple(const char *initiator, const char *url);
+
+int T0170_unmap_simple(const char *initiator, const char *url);