A retrospective review was undertaken of 409 consecutive patients treated with adjuvant radiotherapy for Stage I seminoma between 1988 and 1997. A total of 339 men were treated to a volume encompassing the para-aortic nodes and 70 were treated with extended field radiotherapy. The patients were followed up within oncology clinics adhering to a standard protocol of clinical examination, chest radiography and measurement of serum marker levels. No routine computed tomographic (CT) scans were carried out. At a median follow-up of 57 months, 13 patients have relapsed, giving a recurrence-free rate of 97.2% at 3 years and 96.8% at 5 years. Of these, eight (62%) were detected at routine appointments and five (38%) requested early appointments. Chest radiography (2/5) and serum marker levels (3/5) identified disease in asymptomatic patients. Eight patients (62%) had raised markers at relapse, including two with normal serum markers at original presentation. The median size of pelvic node recurrences in the para-aortic-treated group was 7.3 cm (2.8-13 cm). Four patients have developed second testicular primaries: three were detected at routine appointments and one patient had requested an early appointment. We conclude that regular follow-up with serum marker estimations and chest radiography is sufficient to detect recurrence at an early stage and that our policy of no routine CT scanning has been shown to give acceptable results.