Self-report questionnaire data from 3,000 adult twin pairs participating in the 1988-1989 follow-up survey of the Australian NH&MRC twin panel were analyzed to determine (1) the contribution of genetic factors to risk of problem drinking in males and females; and (2) the magnitude of the correlation between genetic effects on problem drinking and genetic effects on alcohol consumption level. Significant genetic contributions were found both for average weekly consumption of alcohol and for problem-drinking history. For level of consumption, genetic factors accounted for approximately 58% of the variation in females and 45% of the variation in males. Heritability estimates for problem drinking, though significantly greater than zero, were variable in magnitude, ranging (under different models) from 8-44% in females and 10-50% in males. Likewise, estimates of the magnitude of the genetic correlation, whilst in all cases significantly greater than zero, ranged from 0.42-1.00 in females and 0.45-1.00 in males under different models.