In 1979 through 1980, electroencephalographic (EEG) responses to an alcohol challenge in 19 year-old sons of alcoholics as well as in sons of nonalcoholic control subjects were examined. The familial risk status of the subjects and greater EEG sensitivity to alcohol were hypothesized to predict the development of alcoholism 10 years later.In 1990 through 1992, diagnostic interviews were completed to ascertain alcohol and other substance use disorders in these subjects and to update their family history.Updated family history of alcoholism predicted the development of substance dependence. Density of alcoholic relatives (the number of alcoholic relatives divided by the number of known relatives) was positively related to the severity of alcohol use disorders in the probands. Contrary to expectation, a greater EEG response at age 19 years was not related to the later development of alcohol dependence. Instead, the opposite was observed: a smaller EEG alpha frequency response to alcohol at age 19 years was related to the development of alcohol dependence and high quantity and frequency of alcohol consumption 10 years later.Lower EEG response to a small dose of alcohol may be associated with the later development of alcohol dependence. This result is based on a small number of subjects and should be interpreted with caution. Although this result is opposite to our 1980 hypothesis, it is consistent with much of the recent literature.