Background and Purpose: Radiotherapy remains the treatment of choice for patients with stage I seminoma. The aim of this study is to report preliminary results of reduced dose radiotherapy to ipsilateral pelvic and para-aortic lymph nodes. Materials and Methods: Between February 1996 and December 2001, 53 patients with stage I testicular seminoma were treated with adjuvant radiotherapy after orchiectomy. The median age was 34 years (19-59 years). Four (7.5%) patients had a history of cryptorchidism. Eleven (20.8%) patients showed elevated beta-human chorionic gonadotropin. All patients had a radical inguinal orchiectomy and histopathological analysis yielded classic seminoma in 47 (88.7%), spermatocytic in 5 (9.4%) and anaplastic in 1 (1.9%) patients. A total of 19.6-20 Gy in 1.8- to 2-Gy daily fractions was administered to the para-aortic and ipsilateral iliac lymphatics. Results: Median follow-up time was 42 months (12-77 months). One patient developed para-aortic lymph node recurrence at month 28 of the follow-up. Five-year overall and disease-free survivals were 100 and 98%, respectively. Only grade I-II of the Radiation Therapy Oncology Group acute gastrointestinal complications without any severe late toxicity was detected. Conclusion: Reduced dose radiotherapy seems to be as effective as higher doses in the management of stage I seminoma with an acceptable toxicity. Copyright (C) 2003 S. Karger AG, Basel.