The present study evaluated the efficacy of 25 mg of quazepam, a new benzodiazepine hypnotic, in a population of chronic insomniacs. The results indicate that a single dose (25 mg) administered for one night was efficacious when measured both objectively by polysomnographic recording and subjectively by questionnaire with no reported side-effects. The change in the objective measures paralleled the direction of change in subjective measures. Sleep efficiency and sleep maintenance were improved without EEG changes in Stages 2, 3-4, and REM. Further study is needed to evaluate the effects of chronic administration of different doses of quazepam in chronic insomniacs.