To evaluate the treatment-related late sequelae including gonadal function and second malignancy 94 patients with stage I and II testicular seminoma treated with postorchiectomy radiation therapy were analyzed retrospectively. The 10-year cause specific, disease free and actuarial survival rates were 100, 98.5 and 96.1% for stage II and 91.7, 83.3 and 91.7% for stage II, respectively. The most common late sequelae of gastrointestinal tract was peptic ulcer, developing in 16% of all patients with a median interval of 12 months, but severity was mild except one who needed subtotal gastrectomy. Second malignancies developed in 9 patients (9.5%) with a median interval of 13 years, but calculated O/E ratio excluding 2 patients with secondary germ cell tumor of contralateral testis was 2.3 and did not reach a significant level statistically. Concerning gonadal function assessed from the number of the children, 79% of the patients who wanted to have children after the treatment were successful in fathering children. No fatal complications were observed.