We studied five male nonobese patients (mean age, 61 years) who had moderate chronic obstructive pulmonary disease (COPD). Each patient underwent three successive nights of systematic monitoring of sleep variables. On nights 2 and 3, patients received placebo and flurazepam (30 mg). Patients were also given flurazepam (15 mg) for seven consecutive nights and underwent sleep monitoring on nights 1 and 7. Two patients exhibited oxygen desaturation during rapid-eye-movement (REM) sleep, both spontaneously and after administration of flurazepam. The three other patients had no nocturnal oxygen desaturation, either spontaneously or after ingestion of flurazepam. We concluded that sleep-induced respiratory abnormalities are not systematically worsened by flurazepam. Flurazepam (15 mg) had no effect on the sleep disturbances of our patients with COPD after seven nights of administration.