// String BrowserCaption = "Selection a directory";
// String RootPath = "C:";
Shell32.ShellClass shl = new Shell32.ShellClass();
Shell32.Folder2 fld = (Shell32.Folder2)shl.BrowseForFolder(0, BrowserCaption, 0, RootPath);
if (fld != null) // Correspond a Dialog.Result.OK
{
//Console.WriteLine(fld.Self.Path);
// Votre Code
}