Most studies with zopiclone, a cyclopyrrolone derivative with a short elimination half life (5 h) have compared its hypnotic activity with that of long elimination half life molecules. In this double-blind study in geriatric patients, drugs were administered during 3 weeks and the therapeutic effects of zopiclone at optimal dosage (5 or 7.5 mg) were compared to those of triazolam (0.125 or 0.25 mg). After a 3 day single-blind washout period, placebo responders were excluded and 48 patients were thereafter treated with either placebo (Tétreault et al., 1965), zopiclone or triazolam (Pegram et al., 1980). The initial dosage was increased when indicated at the end of the first week and kept constant thereafter. At the end of the third week of double-blind treatment, a 4 day single-blind placebo washout was performed to assess drug withdrawal effects. Results confirmed the safety and efficacy of both drugs over placebo during active administration. Hypnotic activity was maximal at 7.5 mg of zopiclone and 0.25 mg of triazolam. Drug efficacy was found constant over the 3 week administration both for triazolam and zopiclone. During withdrawal, no true rebound effect was demonstrated but the active drugs were significantly worse than placebo during the first day for sleep onset duration, sleep soundness and quality of sleep. With triazolam some effects persisted up to the third day of withdrawal.