A withdrawal syndrome is described in 10 patients who claimed to be unable to discontinue benzodiazepines. A high dose group took the equivalent of a mean of 135 mg diazepam/day, and the normal dose group 20 mg/day. Associated with the gradual reduction of medication was the emergence of severe symptoms of anxiety as well as sensory intolerance, perceptual disturbances and weight loss. The withdrawal syndrome subsided after 2 weeks and was similar in both groups of patients. EEG changes were detected on withdrawal opposite to those known to be associated with initiation of diazepam treatment. The measures tended to revert to the baseline after a drug-free period. One reason why chronic users of diazepam experience difficulty in stopping medication may be the development of a withdrawal syndrome even after moderate dosage.