Pulmonary Hodgkin's disease (HD) is considered to carry a poor prognosis both at presentation and at relapse. We have therefore studied the incidence and significance of pulmonary involvement in 190 poor risk HD patients undergoing BEAM therapy and ABMT for relapsed or resistant disease. Forty-one of 190 patients (22%) had clinically diagnosed pulmonary HD at some stage of their disease prior to ABMT. In 29 patients, in whom a full set of CT scans was available, the patterns of pulmonary HD were characterised. Four of 29 patients had pulmonary disease at presentation only, 8 of 29 at presentation and ABMT and 17 of 29 developed pulmonary involvement at relapse and proceeded to ABMT with persistent pulmonary disease. The commonest pulmonary abnormalities at presentation and relapse were discrete nodules (72%), masses extending from hilar or mediastinal nodes (34%) and pleural effusion/thickening (28%); 52% had two or more patterns of involvement and 66% had coexistent mediastinal lymphadenopathy. There was no relationship between pattern or bulk of pulmonary involvement and outcome. Consideration of the outcome following ABMT in all 190 patients revealed no significant difference in progression-free survival at 5 years between the pulmonary HD group (43%) and those without lung involvement (48%). Furthermore, there was no significant difference in complete remission or transplant-related death rates between the two groups. This would suggest that pulmonary involvement is not in itself a contraindication to ABMT and some patients with bulky pulmonary disease are capable of long-term survival.