In a prospective study of 349 patients with acute poisoning treated at The Montreal General Hospital in 1972 benzodiazepines and non-barbiturate hypnotics were found to be the most frequent putative drugs. Of the 108 patients admitted to hospital 37% had taken an overdose of a drug prescribed for them by their psychiatrist or other physician; 48% had formerly taken an overdose of drugs and 44% had had previous psychiatric treatment. Unconsciousness, respiratory depression, metabolic acidosis and acidemia, and hypokalemia were the most frequent clinical abnormalities observed. Treatment was supportive. There were six deaths. The average duration of coma was short; only five surviving patients remained unconscious for more than 24 hours. Respiratory complications were frequent.It is recommended that more attention be paid to recognizing patients whose behaviour pattern might include such an impulsive gesture, and that alternatives be found for barbiturate and non-barbiturate hypnotics.