Alcohol exerts a series of different effects, especially when ingested chronically, and alcoholism is a rather complex, heterogeneous disease. Genetic factors may be implicated on various levels such as metabolism, acute effects, tolerance, dependence, and medical complications. This presentation will be arranged in three parts: (1) The main results of investigations on alcohol effects on the central nervous system as measured by the electroencephalogram (EEG) will be given. (2) What is known about genetic aspects of alcoholism will be shortly summarized. (3) Possible genetically determined mechanisms that contribute to alcohol preference in man will be discussed.