As MB can import iTunes library via "File> Import from Library" command, it's also possible to export MB library to iTunes. Part of these instructions use a method introduced in an Apple's online support document (http://support.apple.com/kb/HT1451). Verified with the latest, at the time of writing, version of MB(2.3.5137) and iTunes(184.108.40.206). [verified again with MB (2.4.5358) & iTunes (220.127.116.11)]
1. Go to MB's Edit> Preferences> Library and tick "Save a copy of the library tags as an iTunes formatted XML file" option. Then MB will create "iTunes Music Library.xml" file in its library folder and keep it updated whenever any changes are made on MB library files.
2. Locate iTunes library folder (probably \Users\<user>\Music\iTunes) on your PC and delete "iTunes Library.itl" file and "iTunes Music Library.xml" file.
3. Launch iTunes and go to File> Library> Import Playlist. On the pop-up box, navigate to the MusicBee library folder (probably \Users\<user>\Music\Library) and select "iTunes Music Library.xml" file.
You're done! Just wait until iTunes finishes importing your library.
1. iTunes cannot handle multiple values for tags. If you have any multi-value tags such as Artist or Genre, iTunes will import only first value for those tags.
2. All auto-playlists and static playlists, including those in playlist folders, will be imported as static playlists.
3. MB's inbox files get imported as well under "inbox" static playlist.
4. Ratings (either saved to files or database) and Play Count will be correctly imported to iTunes. But iTunes doesn't support half-stars, dropping each half-star from ratings while importing.
5. Video files under MB Video node are imported to iTunes Movies node, but files under MB Audiobooks node are imported to iTunes Music node. It seems only audiobooks purchased from iTunes Store may get imported under iTunes Books node, but it's not verified.
6. iTunes does not use ReplayGain tags but its own SoundCheck values for normalizing playing volume. If your files don't have SoundCheck tag (http://getmusicbee.com/forum/index.php?topic=9600.0), iTunes will analyze volume level of tracks when importing your library if SoundCheck feature is enabled in iTunes' preferences settings.
7. If your music file contains a semicolon in its URL (either folder name or filename), iTunes cannot import the file, reporting it cannot locate the file. However, Add file/folder to library commands can import such files.