Zopiclone was given for 14 nights to 68 geriatric patients (mean age 81 years) with sleep problems. The patients were randomly allocated to four treatment groups: 3.75 mg, 5.0, 7.5, or 10.0 mg of zopiclone. Sleep quantity and quality, side effects, and influence on psychomotor performance (digit symbol substitution and letter cancellation test) were studied before treatment, during active treatment, and after withdrawal of the drug. All patients slept better on zopiclone compared to placebo. There were only slight differences between the different dose levels as regards quantity and quality. No influence on psychomotor performance could be shown. The side effects were mild. Zopiclone showed a good hypnotic efficacy, and 7.5 mg is probably the best dose for elderly patients.