Male hypogonadism, manifested by decreased serum testosterone levels, is an important cause of morbidity and mortality in patients older than 40 years. Its prevalence is proportional to age, and several clinical manifestations, as physical, psychological and sexual, lead to a marked clinical deterioration. The impact of testosterone deficiency on the cardiovascular system accelerates the progression of coronary artery disease, decreases insulin sensitivity and increases overall mortality. American Society for Endocrinology accepted serum values lower than 300 ng/dL as a diagnostic support. To define the start of testosterone replacement therapy should always include clinical and laboratory measurements. Systemic therapy effects will be reflected in the fatigue eradication, libido improvement, and better control of cardiovascular risk factors, including decreased abdominal fat, improved insulin sensitivity, lipid profile, arterial blood pressure, and in some cases, reduction of the mortality.