Zopiclone, a non-benzodiazepine hypnotic, was compared with temazepam in the treatment of 36 patients suffering from insomnia; the trial period was two weeks, with cross-over of medications at one week and a randomised order of administration. There were highly significant improvements with both drugs, as compared to the control period in respect of: sleep latency, number of times waking during the night, and quality and duration of sleep. The incidence of side-effects was very low. No significant between-drug differences were found in respect to any of the assessment measures or of the incidence of side-effects.