Rats were maintained 16 weeks on a well-balanced, semisynthetic, solid diet supplemented with ethanol, which comprised 35% of total calories. A control group was pair-fed the same basic diet with sucrose replacing ethanol isocalorically. On light microscopy, the ethanol-fed rats showed appreciable fatty changes in the liver, while the controls did not. There were no differences in testicular morphology between ethanol-fed and control rats, both of which appeared to be normal. The present findings support the view that ethanol is directly toxic to the liver, but under the present experimental conditions, not directly toxic to the testes.