Chronic heart failure is one of the most common heart diseases and is a leading cause of morbidity and mortality. There has been a rapid growth in knowledge and understanding of the pathogenesis of chronic heart failure in recent years. Tumor necrosis factor (TNF-'), a pro-inflammatory cytokine, is found to play an important role on the development and progression of heart failure. Recent evidence suggests that testosterone improves cardiac function and clinical symptoms in patients with chronic heart failure. Recent experimental studies show that testosterone suppresses the biosynthesis of TNF-' while increasing the levels of anti-inflammatory faction, interleukin-10. Therefore, we hypothesize that testosterone may also suppress the biosynthesis of TNF-' and re-balancing the pro- and anti-inflammatory mechanisms in human hearts, leading to significant improvement in cardiac function and symptoms in patients with chronic heart failure.