diff --git a/lib/AuthorizeNetGateway.js b/lib/AuthorizeNetGateway.js
index 4cb9a50..fa446ba 100644
--- a/lib/AuthorizeNetGateway.js
+++ b/lib/AuthorizeNetGateway.js
@@ -139,6 +139,12 @@ AuthorizeNetGateway.prototype.submitTransaction = function submitTransaction (or
     }
   };
 
+  if(order.invoiceNumber !== undefined) {
+    body.order = {
+      invoiceNumber: order.invoiceNumber
+    }
+  }
+
   if (prospect) {
     body.billTo = mapKeys(prospect, billToSchema);
     body.shipTo = mapKeys(prospect, shipToSchema);
@@ -176,6 +182,12 @@ AuthorizeNetGateway.prototype.authorizeTransaction = function authorizeTransacti
     }
   };
 
+  if(order.invoiceNumber !== undefined) {
+    body.order = {
+      invoiceNumber: order.invoiceNumber
+    }
+  }
+
   if (prospect) {
     body.billTo = mapKeys(prospect, billToSchema);
     body.shipTo = mapKeys(prospect, shipToSchema);