A subject will be re-treated when he/she attains grade 2 (Moderate) or 3 (Severe) in the investigator's and subject's ratings of the severity of glabellar rhytides at maximum frown on a 4-point categorical scale, but not earlier than 90 days following the prior treatment. The subject will call the site when he/she rates the glabellar rhytides as grade 2 or 3 in severity to schedule an appointment for re-evaluation and possible re-treatment. The appointment must occur within 2 weeks of the subject's call but not earlier than 90 days post the previous injection. If at the clinic visit the subject's glabellar rhytides are graded by the investigator as grade 2 or 3 in severity and other eligibility criteria are met (e.g., negative urine pregnancy test in female subjects of childbearing potential), the subject will be re-treated. If a subject is eligible for re-treatment on or before 90 days post the previous injection, he/she will receive treatment of Mentor Purified Toxin on or after 90 days. If a subject is not eligible for re-treatment at 90 days, he/she can return to the clinic monthly until attaining grade 2 (Moderate) or 3 (Severe) in the investigator's and subject's ratings of the severity of glabellar rhytides at maximum frown on a 4-point categorical scale, at which time he/she will receive another treatment of Mentor Purified Toxin.