The records of 40 patients with seminoma of testis were reviewed; nine had cryptorchidism. The incidence of cryptorchidism among the 36 Chinese patients was 22% (8/36). All Stage I and four Stage II patients were treated by orchidectomy followed by radiotherapy of 30 Gy or more to the pelvic and para-aortic lymphatics, while another seven Stage II patients received pelvic and para-aortic lymphatics plus mediastinal irradiation. For patients with normally-descended testis, the 2-year survival for Stage I was 94% and Stage II, with small and clinically unpalpable abdominal nodal metastases, 86%. For patients with Stage I and II seminoma arising from cryptorchid testis, comparable survival can be achieved by giving similar doses of radiation and adjusting the size of the para-aortic and pelvic radiation fields to cover the known extent of the disease. The prognosis of patients with seminoma arising from cryptorchid testis depends more on the stage and extent of disease than the status of cryptorchid testis. Painful groin mass or abdominal pain were the presenting symptoms in more than half of the patients with cryptorchid testes. The changed symptomatology in this group of patients can result in diagnosis delay.