The authors studied the effect of the tranquilizer phenibut on sleep disturbances in alcoholics at the initial period following alcohol withdrawal. Sleep was registered polygraphically during 2 nights in 12 patients taking the drug and in 10 control patients. The drug did not affect the latent period of falling asleep, increasing, however, the duration of two major phases of sleep and reducing the duration of the drowsiness stage. There was no marked influence on the subjective assessment of sleep.