A Redirect like that would cause a loop IF located in the domain.com's DocumentRoot. TB's code is accurate, correct and the most efficient use of mod_rewrite. Your "it doesn't work" is a useless comment, though, as you did not give any indication of what's not working (if mod_rewrite is not enabled, you should get 500 errors; if it is, .htaccess should be the file examined by Apache - you are using Apache, aren't you? - and the code is picture perfect).
As usual (with mod_rewrite questions), please specify EXACTLY what you're trying to do and provide us with the code you're using as the code often has some error which can be quickly spotted by the trained eye.