Female Wistar rats were pair-fed a diet containing either ethanol (5%) or isocaloric carbohydrate substituent. After 6 weeks, a single dose (5 micrograms/kg) of levonorgestrel was given to the animals in each group either orally, subcutaneously or intravenously. Plasma levels of levonorgestrel at different time intervals were measured by RIA. Chronic alcohol administration did not affect plasma levels of levonorgestrel after oral administration. When the drug was given subcutaneously, plasma levels and AUC were significantly decreased in the alcoholic compared to control group. Following intravenous administration, the elimination half-life of levonorgestrel was shorter while the metabolic clearance was higher in the alcohol-treated group rather than the control group.