We added phenylpropanolamine OROS (Acutrim; Ciba-Geigy Corp.) or placebo to a physician-managed behavior modification, mild caloric restriction, and exercise weight control program. One hundred six healthy, overweight (115% to 130% ideal body weight) women participated in this 14-week double-blind clinical trial. On average, the participants who took Acutrim lost significantly more weight (X +/- SE; 6.1 +/- 0.6 kg; 8.0% +/- 0.8%) than did those taking placebo (4.3 +/- 0.7 kg; 5.5% +/- 0.8%; P less than 0.05). Those taking Actrim continued to lose weight over the Christmas holiday, while the placebo group gained weight. Fifteen participants taking placebo withdrew, three because of adverse drug reactions (ADRs). Thirteen of 53 participants in the Acutrim group left the study, two because of ADRs. Dry mouth was the most frequent complaint from participants taking Acutrim. No serious cardiovascular effects occurred. Both complaints and the number of participants reporting ADRs decreased with continued dosing. We conclude that Acutrim is a safe, modestly effective adjunct to a physician-managed, integrated weight control program.