- Late onset hypogonadism (LOH) is a shortage of testosterone in adult men whose male development was normal. This form of hypogonadism results in decreased testosterone levels and variable gonadotrophin levels. - The symptoms of LOH are often aspecific and may be consistent with ageing in men: lowered libido, loss of strength, reduced cognitive functioning and disorders of sleeping and mood. - There is discussion about testosterone parameters, but if clinical symptoms are consistent with LOH and the testosterone level is < 8 nmol/l, hypogonadism is evidently indicated. - The first step is giving advice on lifestyle and treating comorbidity. In addition, treatment with testosterone may be given. - Testosterone has a positive effect on sexual function and vitality. Testosterone therapy for hypogonadism decreases the risk of osteoporosis. Contraindications are advanced prostate cancer and the desire to have children. - If a patient is treated with testosterone, strict follow-up is recommended; testosterone, haematocrit and PSA levels should be determined at set intervals.