We studied the in vivo effects of the peptide anxiolytic selank (0.3 mg/kg) on the behavioral parameters of the syndrome of alcohol withdrawal and the neurochemical indices of the serotonergic system in the brain structures in ex vivo experiments in outbred rats with a preference for a 10% solution of ethanol. We found that a single administration of selank eliminates the anxious response in the elevated plus maze at 48 h after the withdrawal of ethanol and increases the time spent in the open arms and the number of entries into the open arms. Using HPLC, we showed that selank prevents an increase in the serotonin level in the frontal cortex, hypothalamus, and amygdala, which may be related to a decrease in the synthesis of serotonin. The data we obtained indicate that selank has anxiolytic activity under conditions of alcohol abstinence, which suggests that the sphere of its use in clinical practice may be widened.