Certain forms of alcoholism have been shown to be familial and to be related to both genetic and environmental factors. Until a biological, genetic marker (or markers) can be identified, however, a careful family history will continue to be the only method of accurately diagnosing familial alcoholism. The family physician is in a unique position to make the diagnosis and to identify and selectively counsel family members at risk before alcohol consumption becomes a problem and, preferably, before drinking decisions are made.