This paper is based on a lecture given during the Oncological Forum, Oslo, in November 2002. Long-term morbidity in cancer survivors is exemplified by results of clinical research in testicular cancer survivors (TCSs). The most serious complication is the development of second, non-germ cell malignancies (relative risk [RR]: 1.4-1.6). After infradiaphragmatic radiotherapy, most solid malignancies are diagnosed within or near the target volume. Combined chemo-radiotherapy increases this risk. Chemotherapy-induced leukaemia is usually reported after 4-7 years. After 3 or 4 cycles of cisplatin-based chemotherapy, 15-20% of TCSs suffer from peripheral sensory neuropathy, Raynaud-like phenomena and/or ototoxicity. Hypogonadism is observed in 16%. The risk of cardiac complications is increased by hypercholestorolaemia and abnormal body mass. Pelvic radiotherapy and cisplatin-based chemotherapy are followed by transient oligo/azospermia with recovery after 6-12 months. The risk of surgery-related 'dry ejaculation' is significantly reduced after unilateral and nerve-sparing retroperitoneal lymph node dissection, but infertility remains a long-term problem in 10-15% of survivors. Most TCSs describe their quality of life as comparable with that of the age-matched male general population. Not all long-term complications are avoidable after curative treatment of cancer. Knowledge of post-treatment long-term morbidity is essential for early recognition and treatment of late complications, and enables adequate counselling of new cancer patients.