With the increasing success of multimodality anticancer therapy, most men of reproductive age will survive their malignancy. Reproductive function is a principal concern of these men. Health-care providers are shifting the focus of oncologic care toward improving the quality of life in cancer patients, particularly with regard to fertility. For unknown reasons, fertility and sexual function are adversely affected in men with germ cell tumors and Hodgkin's disease prior to the initiation of therapy. Despite these pretreatment abnormalities, fertility potential remains good. Cancer therapy utilizing physical and chemical treatment methods can temporarily or permanently damage spermatogonia, resulting in azoospermia and infertility. Recovery of spermatogenesis can take up to 10 years after therapy. Alternative treatment regimens can preserve reproductive function while maintaining high therapeutic efficacy. Surgical treatment should be directed toward maintaining the neurovascular mechanisms responsible for seminal emission and ejaculation. With new developments in assisted reproductive techniques, even cancer patients with severe oligoasthenospermia can father children. These techniques have not been found to increase the incidence of major or minor birth defects.