An ever-increasing proportion of young males treated for cancer are cured. Therefore, one of the major challenges of modern Clinical Oncology is to ensure good quality of life. Cancer disease per se as well as cancer treatment may have a negative impact on androgen production, thereby leading to subclinical or clinically overt hypogonadism. Since the symptoms of androgen deficiency are rather unspecific, it is important that reproductive hormone levels be checked in young men who have been treated for cancer. As androgen deficiency in men is associated with increased long-term risk of osteoporosis as well as cardiovascular and metabolic disease, those cancer survivors who present with signs of insufficient androgen production should be followed and preventive as well as therapeutic measures, including androgen replacement therapy, should be applied according to the current guidelines.