Oral estrogen therapy for prostatic cancer is clinically effective but also accompanied by severe cardiovascular side effects. Hypertension, venous thromboembolism, and other cardiovascular disorders are associated with alterations in liver metabolism. The impact of exogenous estrogens on the liver is dependent on the route of administration and the type and dose of estrogen. Oral administration of synthetic estrogens has profound effects on liver-derived plasma proteins, coagulation factors, lipoproteins, and triglycerides, whereas parenteral administration of native estradiol has very little influence on these aspects of liver function.