Is valid GUID
using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Text.RegularExpressions; public static class UtilityExtension { public static readonly Regex guidRegEx = new Regex(@"^(\{{0,1}([0-9a-fA-F]){8}-([0-9a-fA-F]){4}-([0-9a-fA-F]){4}-([0-9a-fA-F]){4}-([0-9a-fA-F]){12}\}{0,1})$"); public static bool IsGuid(this string expression) { if (!String.IsNullOrEmpty(expression)) { return guidRegEx.IsMatch(expression); } return false; } }