The results of computer-analyzed electroencephalographic (EEG) data from 24 sons of alcoholics (family history positive [FHP]) and their matched controls (family history negative [FHN]) were compared before and 90 minutes following alcohol and placebo challenge. Blind analysis of the data revealed that FHP men had more energy in the fast-frequency alpha range (9 to 12 Hz) of their EEG than did FHN subjects at baseline. EEG response to ethanol was also found to differ between the two groups. FHN but not FHP subjects evidenced a decrease in fast-frequency alpha energy following ethanol challenge. These data support other evidence of a less intense reaction to ethanol in FHPs as measured by subjective response, body sway, and hormone levels. In addition, these findings suggest that certain normal alpha wave variants may be more common in sons of alcoholics.