The decline in Testosterone (T) levels in the ageing male - known as andropause or late-onset hypogonadism - may be responsible for several aspects of quality of life decline in older men: erectile dysfunction, impaired libido, decreased strength and energy, sarcopenia, osteopenia, fatigue and even depression in some cases. Many of these signs and symptoms represent the same alterations that are usually attributed to the process of ageing. When some individual presents with such symptoms, hypogonadism should be suspected, and serum T level should be evaluated. Men who are symptomatic and present low levels of serum Testosterone (generally below 300 ng/ml) are candidates for T replacement therapy. Current evidence shows that, when correctly selected, patients receiving T replacement may benefit from improvement in libido, erectile function, overall and sexual related quality of life, bone density and muscle mass. Conversely, patients with physiological circulating levels of T who receive hormone, aiming at supraphysiologic levels, may face severe side effects, including testicular atrophy and behavioral changes. Of note, T replacement, regardless of age and pre-therapy levels, leads to fertility impairment which can be transient or persistent. Direct testosterone replacement should not be indicated in men who wish to conceive children, although other options are available. The effect of Testosterone replacement on prostate cancer and on cardiovascular risk is still controversial; hypogonadal men known to have prostate cancer or high cardiovascular risk should be examined individually to have their risks stratified and mitigated.