Event-related potentials (ERPs) were studied during deceptive and truthful responses of subjects that were in the normal state or under the influence of alcohol. The psychological task was designed in such a way that the subjects themselves decided whether or not they would tell a lie. Thirteen healthy volunteers participated in the study. An actual deceptive answer was characterized by a higher amplitude of the frontocentral ERP N190 component compared to the ERP accompanying a truthful answer. Alcohol consumption inverted the ratio between the amplitudes of this component in the cases of deceptive and truthful answers (with a higher amplitude in the latter case). The obtained result suggests that a deceptive action activates the so-called cerebral error detector. Under the influence of alcohol, the cerebral error detection system functioned abnormally, so that a deceptive action was not perceived as erroneous. This disturbance of automatic control may account for the lower amplitude of the late positive component of ERPs, which, in our opinion, reflects the process of making a decision on a deceptive response. This may explain why, e.g., alcohol consumption by a driver is hazardous: the activity is mainly controlled by conscious processes (the probability of making "the only right decision" in a critical situation is decreased, reactions become slow, etc.). Thus, the experimental model where the subject consumes a small amount of alcohol may be used for studying the altered functional mode of the cerebral error detector. Such studies seem promising in terms of searching for and developing methods for noninvasive modification of the error detector activity that could be used, e.g., in treatment for obsessions.