After a period of forced exposure to alcohol, rats developed a preference for alcohol when given the choice to drink either an alcohol solution or water. The development of alcohol preference was dependent on the alcohol concentration but independent of the presence of an alcohol withdrawal phase. The highest alcohol consumption was found with a 3% sohtion. The serotonin 5-HT2 antagonist ritanserin reduced alcohol intake and alcohol preference in a dose-related manner. Changes in test procedures and injection schedules did not affect the effectiveness of ritanserin. The activity of ritanserin started at doses 20.04 mg/kg and in the active dose range ritanserin reduced alcohol intake by 46 to 67% and alcohol preference by 33 to 42%. At any time during treatment, the decrease in alcohol drinking was compensated by an increase in water consumption. As a consequence, total fluid intake remained constant. Body weight gain in ritanserin-treated rats was not different from vehicle-treated animals. Discontinuation of ritanserin treatment in animals with a very low alcohol intake during ritanserin treatment resulted within one week in a gradual increase in 3% alcohol solution drinking up to 50% of total intake. In rats with a high alcohol preference ritanserin initiated water drinking again. Additional experiments showed that ritanserin neither directly interacted with the discriminative stimulus properties of alcohol nor induced a direct alcohol aversion. The activity of ritanserin against alcohol is discussed in terms of a serotonin 5-HT2 antagonism that reduces the need for alcohol after a chronic exposure to alcohol.