Fifty-one psychoneurotic outpatients participated in a study in which the effects of four drugs were compared. The main symptoms were anxiety, tension, and mild depression, in the absence of detectable organic disease. Complete data were obtained from 28 patients who took all four drugs in random order. The drugs were given each four times a day for two weeks in the following doses: amobarbital sodium, 30 mg.; meprobamate, 400 mg.; prochlorperazine, 5 mg.; and placebo. Precautions were taken to eliminate bias arising from personal interactions, from the order in which the drugs were taken, or from the fact that 23 patients dropped out before completing the study. The three active drugs and the placebo all influenced the patients significantly during the first two weeks, but thereafter only the three active drugs gave significantly better results. Therapy with meprobamate always produced the most marked change toward improvement and most often showed a significant difference between drug and placebo in the dosages used.