int count = 1; string fileNameOnly = Path.GetFileNameWithoutExtension(fullPath); string extension = Path.GetExtension(fullPath); string path = Path.GetDirectoryName(fullPath); string newFullPath = fullPath; while(File.Exists(newFullPath)) { string tempFileName = string.Format("{0}({1})", fileNameOnly, count++); newFullPath = Path.Combine(path, tempFileName + extension); }