diff --git a/outscale/resource_outscale_load_balancer_vms_test.go b/outscale/resource_outscale_load_balancer_vms_test.go
index 7116493a2..2b894688a 100644
--- a/outscale/resource_outscale_load_balancer_vms_test.go
+++ b/outscale/resource_outscale_load_balancer_vms_test.go
@@ -18,6 +18,7 @@ func TestAccVM_WithLBUAttachment_basic(t *testing.T) {
 	var conf oscgo.LoadBalancer
 	omi := os.Getenv("OUTSCALE_IMAGEID")
 	rand := acctest.RandIntRange(0, 50)
+	region := utils.GetRegion()
 	testCheckInstanceAttached := func(count int) resource.TestCheckFunc {
 		return func(*terraform.State) error {
 			if conf.BackendVmIds != nil {
@@ -37,7 +38,20 @@ func TestAccVM_WithLBUAttachment_basic(t *testing.T) {
 		CheckDestroy:  testAccCheckOutscaleLBUDestroy,
 		Steps: []resource.TestStep{
 			{
-				Config: testAccOutscaleLBUAttachmentConfig1(rand, omi, utils.GetRegion()),
+				Check: resource.ComposeTestCheckFunc(
+					testAccCheckOutscaleOAPILBUExists("outscale_load_balancer.bar", &conf),
+					testCheckInstanceAttached(1),
+				),
+			},
+			{
+				Config: testAcc_ConfigLBUAttachmentAddUpdate(omi, region),
+				Check: resource.ComposeTestCheckFunc(
+					testAccCheckOutscaleOAPILBUExists("outscale_load_balancer.bar", &conf),
+					testCheckInstanceAttached(2),
+				),
+			},
+			{
+				Config: testAcc_ConfigLBUAttachmentRemoveUpdate(omi, region),
 				Check: resource.ComposeTestCheckFunc(
 					testAccCheckOutscaleLBUExists("outscale_load_balancer.barTach", &conf),
 					testCheckInstanceAttached(1),
@@ -197,3 +211,63 @@ resource "outscale_load_balancer_vms" "foo1" {
 }
 `, region, omi)
 }
+
+func testAcc_ConfigLBUAttachmentAddUpdate(omi, region string) string {
+	return fmt.Sprintf(`
+resource "outscale_load_balancer" "bar" {
+  load_balancer_name = "load-test12"
+  subregion_names = ["%sa"]
+  listeners {
+    backend_port = 8000
+    backend_protocol = "HTTP"
+    load_balancer_port = 80
+    load_balancer_protocol = "HTTP"
+  }
+}
+
+resource "outscale_vm" "foo1" {
+  image_id = "%[2]s"
+  vm_type = "tinav4.c1r1p1"
+}
+
+resource "outscale_vm" "foo2" {
+  image_id = "%[2]s"
+  vm_type = "tinav4.c1r1p1"
+}
+
+resource "outscale_load_balancer_vms" "foo1" {
+  load_balancer_name      = "${outscale_load_balancer.bar.id}"
+  backend_vm_ids = ["${outscale_vm.foo1.id}", "${outscale_vm.foo2.id}"]
+}
+`, region, omi)
+}
+
+func testAcc_ConfigLBUAttachmentRemoveUpdate(omi, region string) string {
+	return fmt.Sprintf(`
+resource "outscale_load_balancer" "bar" {
+  load_balancer_name = "load-test12"
+  subregion_names = ["%sa"]
+  listeners {
+    backend_port = 8000
+    backend_protocol = "HTTP"
+    load_balancer_port = 80
+    load_balancer_protocol = "HTTP"
+  }
+}
+
+resource "outscale_vm" "foo1" {
+  image_id = "%[2]s"
+  vm_type = "tinav4.c1r1p1"
+}
+
+resource "outscale_vm" "foo2" {
+  image_id = "%[2]s"
+  vm_type = "tinav4.c1r1p1"
+}
+
+resource "outscale_load_balancer_vms" "foo1" {
+  load_balancer_name      = "${outscale_load_balancer.bar.id}"
+  backend_vm_ids = ["${outscale_vm.foo2.id}"]
+}
+`, region, omi)
+}