Outcome studies of the value of reduction mammaplasties have only recently appeared in the literature. Medical directors of insurance companies and managed care plans have been reluctant to pay for reduction mammaplasties, citing the uncertainty of the medical necessity of the procedure. They have defended their position by stating that the medical literature is devoid of studies documenting that reduction mammaplasty is medically beneficial to the patient. For this reason, reduction mammaplasty is often excluded from health care benefit plans. Because of the need for outcome studies for this procedure, the charts of 363 consecutive patients who had reduction mammaplasty at the Mayo Clinic from January of 1986 to December of 1993 were reviewed. Questionnaires were sent to all these patients asking them to evaluate their outcome, and 328 responded (90.4 percent response rate). Of the respondents, 94.2 percent believed that the procedure was completely or very successful, and only 1.5 percent believed that it was not very successful or completely unsuccessful. The symptoms most frequently reported by patients preoperatively were as follows: uncomfortable feeling about their body, 97.0 percent; inability to find clothes that fit, 95.7 percent; pain in brastrap groove, 92.4 percent; shoulder pain, 86.0 percent; inability to run, 79.3 percent; upper back pain, 79.0 percent; inability to participate in sports, 77.4 percent; neck pain, 70.7 percent; lower back pain, 64.0 percent; and intertrigo, 61.0 percent. The symptoms least frequently reported by patients preoperatively were as follows: pain or numbness in the hands, 22.6 percent; headaches, 30.2 percent; arm pain, 35.4 percent; and breast pain, 58.2 percent. These symptoms were either relieved or partially relieved in 88 percent or more of the patients. Of the 328 patients, 97.3 percent responded that they definitely or probably would have the procedure again, and only 1.2 percent definitely or probably would not have the operation again. Evaluation of medical treatment used to relieve symptoms showed a marked decrease in the need for such measures after reduction mammaplasty. Study of the charges for the procedure revealed that the setting of practice parameters for the procedure and the use of an ambulatory surgery center significantly decreased the charges for the procedure. This outcome study supports the hypothesis that reduction mammaplasty is an effective procedure and the treatment of choice for symptomatic mammary hyperplasia.