Lately the role of radiotherapy in stage I seminoma of the testis has been questioned by some authors who reported on a "surveillance" strategy for these patients. Since 1980, 124 patients with seminoma of the testis have been referred to this institution; 97 of 116 patients analysed presented with stage I disease and 10 of these had elevated levels of beta HCG. A total of 64 patients were given radiotherapy after orchiectomy and 33 entered a surveillance protocol. After a median follow-up of 48 months, 3 patients in the surveillance group relapsed after 5, 13 and 49 months and 2 of the irradiated patients did so after 25 and 33 months. Elevation of beta HCG was not significant because none of these patients showed progression. A low rate of progression and excellent survival are associated with standard treatment (orchiectomy and radiotherapy) and good results have been achieved with chemotherapy in cases of relapse. A surveillance policy is not recommended in stage I seminoma because of its slower growth compared with non-seminomatous germ cell tumours (NSGCT), the absence of a specific tumour marker, the 10% risk of occult metastases and the 3-fold higher progression rate compared with irradiated patients. We suggest the use of a reduced dosage and radiation field.