Answer by David · Jun 28, 2011 at 06:44 PM
Under "File" in iTunes, select Add Folder to Library... This will allow you add multiple folders at one time.
EDIT: If the files you are importing need to be converted, iTunes will advise you of this and then convert them for you.
What is in your Dock? (Mac Users) 25 Answers
Karaoke Plugin for iTunes? 1 Answer