Testicular dysfunction is a common long-term sequela of cytotoxic chemotherapy used in the treatment of many malignancies. The degree to which testicular function is affected is dose- and agent-dependent. The impact on germinal epithelial function of standard multi-agent regimens used in the treatment of lymphomas has been widely studied. Procarbazine-containing regimens result in azoospermia in the vast majority of patients, but much lesser degrees of long-term gonadotoxicity are apparent with the newer forms of chemotherapy. High-dose chemotherapy used as preparation before bone marrow transplant is also associated with irreversible germinal epithelial failure in the majority of men. Treatment of testicular cancer with cisplatin and carboplatin regimens leads to temporary azoo- and oligozoospermia in most men, with a recovery to normospermia in 80% by 5 years. There is also evidence of mild Leydig cell impairment in a proportion of men treated with cytotoxic agents, although the clinical significance of this is not clear. Several methods of preserving testicular function during potentially sterilizing treatment have been considered. At present, sperm banking remains the only proven method, although hormonal manipulation to enhance recovery of spermatogenesis and cryopreservation of testicular germ cells are possibilities for the future.