diff --git a/src/ajax.js b/src/ajax.js
index 9886fd70f9..a9e13a879e 100644
--- a/src/ajax.js
+++ b/src/ajax.js
@@ -542,7 +542,7 @@ jQuery.extend({
 });
 
 function buildParams( prefix, obj, traditional, add ) {
-	if ( jQuery.isArray(obj) ) {
+	if ( jQuery.isArray(obj) && obj.length ) {
 		// Serialize array item.
 		jQuery.each( obj, function( i, v ) {
 			if ( traditional || rbracket.test( prefix ) ) {
@@ -562,10 +562,15 @@ function buildParams( prefix, obj, traditional, add ) {
 		});
 			
 	} else if ( !traditional && obj != null && typeof obj === "object" ) {
+		if ( jQuery.isEmptyObject( obj ) ) {
+			add( prefix, "" );
+
 		// Serialize object item.
-		jQuery.each( obj, function( k, v ) {
-			buildParams( prefix + "[" + k + "]", v, traditional, add );
-		});
+		} else {
+			jQuery.each( obj, function( k, v ) {
+				buildParams( prefix + "[" + k + "]", v, traditional, add );
+			});
+		}
 					
 	} else {
 		// Serialize scalar item.
diff --git a/test/unit/ajax.js b/test/unit/ajax.js
index b7eb57d8e8..18122b9841 100644
--- a/test/unit/ajax.js
+++ b/test/unit/ajax.js
@@ -390,7 +390,7 @@ test("serialize()", function() {
 });
 
 test("jQuery.param()", function() {
-	expect(19);
+	expect(22);
 	
 	equals( !jQuery.ajaxSettings.traditional, true, "traditional flag, falsy by default" );
   
@@ -419,6 +419,11 @@ test("jQuery.param()", function() {
 	equals( jQuery.param(params,true), "a=1&a=2&b=%5Bobject+Object%5D&i=10&i=11&j=true&k=false&l=undefined&l=0&m=cowboy+hat%3F", "huge structure, forced traditional" );
 
 	equals( decodeURIComponent( jQuery.param({ a: [1,2,3], 'b[]': [4,5,6], 'c[d]': [7,8,9], e: { f: [10], g: [11,12], h: 13 } }) ), "a[]=1&a[]=2&a[]=3&b[]=4&b[]=5&b[]=6&c[d][]=7&c[d][]=8&c[d][]=9&e[f][]=10&e[g][]=11&e[g][]=12&e[h]=13", "Make sure params are not double-encoded." );
+
+	// Make sure empty arrays and objects are handled #6481
+	equals( jQuery.param({"foo": {"bar": []} }), "foo%5Bbar%5D=", "Empty array param" );
+	equals( jQuery.param({"foo": {"bar": [], foo: 1} }), "foo%5Bbar%5D=&foo%5Bfoo%5D=1", "Empty array param" );
+	equals( jQuery.param({"foo": {"bar": {}} }), "foo%5Bbar%5D=", "Empty object param" );
 	
 	jQuery.ajaxSetup({ traditional: true });