Hi, Am using regex.Replace() to replace the whole occurrence of a string.. so I gave like Regex.Replace(str,@stringToReplace,"**"); where stringToReplace = @"session" + "\b"; if i give like that its not replacing.. but if i give like Regex.Replace(str,@"session\b","**"); then its working.. how to avoid this.. i want to pass value which will be set dynamically.. Thanks nimmi