In a collaborative study by several psychiatrists, 135 women and 77 men with symptoms of directly perceived anxiety, phobic reactions, obsessive thinking and compulsive behavior, depression, tension, psychomotor and motor retardation, hysterical acting-out behavior, and conversion reactions were treated with chlordiazepoxide. A favorable response was reported in 80.2%. Initial doses were 25 mg. once or twice a day, increased, in some patients, by increments of 25 mg. to a total maximal daily dose of 175 mg. Maintenance doses ranged from 10 to 150 mg. daily and duration of treatment was from one week to 13 months. The most prominent side-effects, drowsiness and ataxia, were dose-related. The drug was discontinued because of reactions in six (2.8%) instances. Disturbances related to the extrapyramidal system did not occur. Hemograms, urinalyses, and liver function tests remained within normal range.