Injections of botulinum A exotoxin are successfully used to treat neuromuscular disorders and to improve hyperkinetic muscles and dynamic rhytids of the upper face. Using these principles, we extended its use to the treatment of the aging neck (hypertrophic platysma muscle bands). A classification system (I to IV) based on horizontal neck rhytids, platysma bands, and skin laxity was devised to categorize the degree of deformity and serve as a guideline for suggested dosages of botulinum. The results correlated with the degree of age-related neck degeneration. Type II (mild horizontal neck rhytids; thin, mild platysma muscle flaccidity; and mild skin laxity) and III (moderate horizontal neck rhytids; thick, moderate platysma muscle flaccidity; and moderate skin laxity) patients were the most satisfied, followed closely by types I and IV. A total of 1500 patients were treated by three independent practices. The majority of them achieved good-to-excellent results, as evaluated by both the physician and patient. The degree of muscle flaccidity and hypertrophy were the factors that most influenced success rates, not the anatomic variations in muscle configuration.