The distribution of the multiple molecular forms of human liver alcohol dehydrogenase and the specific enzymatic activity of homogenate supernatants were examined in 100 liver specimens from Indianapolis, IN. The specific enzymatic activities of livers with the ADH3 2 phenotype were significantly higher than those with the ADH3 1 or ADH3 2-1 phenotype. By comparison of the electrophoretic pattern and the pH-activity profiles of the homogenate supernatants, sixteen percent of the specimens contained hitherto unknown enzyme forms exhibiting unusual electrophoretic mobility and a pH-optimum of 7.0 for ethanol oxidation. The data confirm that the molecular and catalytic properties of this enzyme are even more diverse than has been known. © 1979.