E pidemiological evidence suggests that the prognosis of heart failure in women is better than in men. In our murine model of dilated cardiomyopathy arising from cardiac-specific overexpression of TNF-α, the 6-month survival rate was significantly better in females than in males. Young female transgenic mice exhibited left ventricular wall thickening without dilatation, whereas age-matched male transgenic hearts were markedly dilated. Basal and isoproterenol-stimulated fractional shortening was preserved in female transgenic mice, but not in male transgenic mice. Myocardial expression of proinflammatory cytokines and the extent of myocardial infiltrates were similar in male and female transgenic mice. Myocardial expression of TNF-receptor mRNAs (type I and type II) was significantly higher in male mice in both transgenic and wild-type littermates, whereas sex-specific differences were not observed in either peripheral white blood cells or liver tissue. After TNF-α challenge, myocardial but not liver production of ceramide was significantly higher in male than in female mice. Thus, differential expression of myocardial TNF receptors may contribute to sex differences in the severity of congestive heart failure and mortality consequent to cardiac-specific overexpression of TNF-α.