Since beef tenderloin is naturally a very tender cut of beef, I think it lends itself beautifully to being roasted to medium-rare.  Obviously, this is personal preference, so if you’re looking to cook your meat to medium or well done, then you should make sure that you stick to these listed internal temperatures as a good guideline using a meat thermometer: - For medium-rare meat, you’ll need to reach an internal temperature of about 130°F - For medium meat, you’ll need to reach an internal temperature of  about 135°F - For medium-well meat, you’ll need to reach an internal temperature of 140°F - For well-done meat, you’ll need to reach an internal temperature of 150°F