Preheat oven to 425 degrees F. Using a paring knife, make several 1/2-inch-deep slits in pork tenderloin. In a small bowl combine garlic, lemon peel, and rosemary. Stuff some of the garlic mixture into each slit in the tenderloin. Place tenderloin on a rack in a shallow roasting pan.
Roast tenderloin for 25 to 35 minutes or until done (155 degrees F).