Alprazolam was compared to diazepam and placebo in 235 outpatients suffering from manifest anxiety. In this 28-day double-blind study, alprazolam was more effective than placebo and essentially equivalent to diazepam in alleviating the symptoms of anxiety. However, alprazolam produced a markedly lower incidence of side effects than either diazepam or placebo. Of particular note, drowsiness was reported less than half as frequently by alprazolam patients than by diazepam patients. These results were achieved with an average daily dose of 1.5 mg alprazolam compared to 18.6 mg diazepam.