The muscular anatomy of the face is complex. Animation patterns of facial muscles vary significantly among individuals. Activity of facial muscles determines expression and emotion and affects the eyes aperture and the amount and extent of facial rhytids. Injection of botulin toxin for facial rejuvenation has become a very popular procedure and allows the practitioner the ability to modulate facial expression and to decrease the amount of facial rhytids. A thorough knowledge of the variant facial anatomy is necessary to maximize the efficiency of botulin toxin injection. This knowledge will also aid in minimizing complication an untoward side effect.