static List<Object> list = new List<Object>() { 1,2,4,"a","b"}; static List<Object> list1 = new List<Object>() { 1, 2, 3,"a","c" }; static void Main(string[] args) { list1.RemoveAll(it => list.Contains(it)); foreach (Object i in list1) { Console.WriteLine(i); } Console.ReadKey();