diff --git a/builtin/providers/cloudstack/resource_cloudstack_instance.go b/builtin/providers/cloudstack/resource_cloudstack_instance.go
index aa894f517..3e2c7d463 100644
--- a/builtin/providers/cloudstack/resource_cloudstack_instance.go
+++ b/builtin/providers/cloudstack/resource_cloudstack_instance.go
@@ -124,6 +124,12 @@ func resourceCloudStackInstance() *schema.Resource {
 				Optional: true,
 				Computed: true,
 			},
+
+			"root_disk_size": &schema.Schema{
+				Type:     schema.TypeInt,
+				Optional: true,
+				ForceNew: true,
+			},
 		},
 	}
 }
@@ -252,6 +258,11 @@ func resourceCloudStackInstanceCreate(d *schema.ResourceData, meta interface{})
 		p.SetGroup(group.(string))
 	}
 
+	// If there is a root_disk_size supplied, add it to the parameter struct
+	if rootdisksize, ok := d.GetOk("root_disk_size"); ok {
+		p.SetRootdisksize(int64(rootdisksize.(int)))
+	}
+
 	// Create the new instance
 	r, err := cs.VirtualMachine.DeployVirtualMachine(p)
 	if err != nil {
diff --git a/website/source/docs/providers/cloudstack/r/instance.html.markdown b/website/source/docs/providers/cloudstack/r/instance.html.markdown
index bc8f6a2d5..9ed4a9db5 100644
--- a/website/source/docs/providers/cloudstack/r/instance.html.markdown
+++ b/website/source/docs/providers/cloudstack/r/instance.html.markdown
@@ -66,6 +66,10 @@ The following arguments are supported:
 * `expunge` - (Optional) This determines if the instance is expunged when it is
     destroyed (defaults false)
 
+* `root_disk_size` - (Optional) The size of the root disk in
+    gigabytes. The root disk is resized on deploy. Only applies to
+    template-based deployments.
+
 ## Attributes Reference
 
 The following attributes are exported: