The purpose of the present study was to examine the effects of alcohol on EEG event-related desynchronization (ERD) and event-related synchronization (ERS) of the 4-6, 6-8, 8-10, and 10-12 Hz frequency bands during an auditory memory task. Twenty subjects performed an auditory memory task during which the EEG was recorded. Half the subjects performed the task without the administration of alcohol and half under the influence of alcohol ( approximately 0.7 g/l). The administration of alcohol itself did not alter the ERD/ERS responses. However, when the effects of alcohol were studied as a function of time and task (encoding vs. retrieval), we observed significant effects in the 4-6, 6-8, and 8-10 Hz frequency bands such that the administration of alcohol decreased the early-appearing ERS responses during auditory encoding and increased the later-appearing ERD responses during retrieval. Our results indicate that alcohol has disorganizing effects on brain electric oscillatory systems in the theta and lower alpha frequency range during cognitive processing.