Growth hormone has previously been shown to increase the activity of alcohol dehydrogenase in primary hepatocyte culture from male rats. In this study, continuous exposure of cultured hepatocytes to growth hormone (1 microgram/ml) resulted in parallel increased in the enzyme activity of alcohol dehydrogenase and immunoreactive protein. Growth hormone increased the incorporation of [3H]leucine into alcohol dehydrogenase protein relative to the incorporation into cytosolic protein. The abundance of alcohol dehydrogenase mRNA increased on Days 3 and 4 of continuous exposure of the hepatocytes to growth hormone and returned to control levels on Day 5 of culture. Growth hormone increased the rate of transcription of the alcohol dehydrogenase gene as demonstrated by nuclear runoff experiments. These observations indicate that the effect of growth hormone in enhancing alcohol dehydrogenase activity is due to increased synthesis of the enzyme which is initiated at the level of gene transcription.