This was an open study of the efficacy and acceptability of zopiclone 7.5 mg nocte as a somnifacient. The study population comprised 108 insomniac patients (70 female, 38 male) aged 22-74 years who received zopiclone 7.5 mg for 7 consecutive nights. Based on subjective sleep assessments, zopiclone reduced the patients' difficulty in falling asleep, increased the number of hours slept and decreased the number of nocturnal awakenings (p less than 0.001). The majority of patients reported sleeping well or very well. The quality of sleep improved (p less than 0.0001), and the incidence of waking earlier than desired decreased (p less than 0.001), with respect to baseline, after receiving zopiclone. Physicians rated efficacy as good or very good in the majority of patients. Zopiclone was efficacious both in patients who had not previously received hypnotic therapy (n = 37) and in patients who transferred directly to zopiclone from a benzodiazepine hypnotic (n = 26). Whilst receiving zopiclone, patients reported feeling better in the morning than they did prior to treatment (p less than 0.004); 78% expressing satisfaction with zopiclone as an hypnotic. Physicians reported zopiclone treatment to be without side-effects in the majority of patients. In conclusion, zopiclone appears to be an effective and well-tolerated hypnotic that may play a role in the treatment of insomnia in the general population.