OBJECTIVE To examine the costs and benefits of routine follow-up evaluation in patients treated with radiation therapy for early-stage Hodgkin's disease. METHODS We retrospectively examined patterns of follow-up evaluation and methods of relapse detection among 709 patients with stage I and II Hodgkin's disease treated with primary radiotherapy between 1969 and 1994. We determined the probability of relapse detection for seven routine follow-up procedures, compared their relative costs, and determined the impact of each procedure on the likelihood of survival following salvage therapy. RESULTS Relapse has occurred in 157 patients (22%) at a median 1.9 years (range, 0 to 13 years) posttreatment. Relapse was suspected primarily by history (Hx) in 55% of patients, physical examination (PE) in 14%, chest x-ray (CXR) in 23%, and abdominal x-ray (KUB) in 7%. Only one relapse (1%) was identified by a routine laboratory study. The rate of relapse detection was highest for a combination of Hx and PE (78 of 10,000 examinations) followed by CXR (26 of 10,000 examinations). The projected charges (1995 dollars) per relapse detected by routine follow-up Hx and PE were $11,000 compared with $68,000 for CXR and $142,000 for KUB. The 10-year actuarial survival rate following salvage therapy was 65% overall, 65% for patients in whom relapse was detected by Hx or PE, and 69% for patients in whom relapse was detected by radiographs (P = not significant). CONCLUSIONS The majority of relapses occurred within 5 years of treatment and were identified by Hx and PE. CXR was useful during the first 3 years of follow-up evaluation. KUB, CBC, and laboratory studies accounted for nearly half of all follow-up charges and rarely led to the detection of relapse. Their routine use as a method of relapse detection is questionable. In general, the method of relapse detection did not have a significant impact on the likelihood of successful salvage therapy.