The outcome of 75 cases of post-radiotherapy pericarditis severe enough to lead to surgery, was reviewed from 1970 to September 1995. Four clinical forms were identified: acute pericarditis resistant to medical treatment (12 cases), large chronic pericardial effusions resistant to medical treatment (16 cases), chronic, compressive effusions (35 cases) and signs of pericardial constriction (12 cases). The medical conditions irradiated were Hodgkin's disease (41 cases), followed by carcinomas (27 cases), malignant lymphomas, thymoma and seminoma. Forty-three deaths were observed during the study period (only 4 unrelated to the neoplasia or radiotherapy) after a mean interval of 7.4 years after radiotherapy and 2.5 years after surgical biopsy: 25 were related to cardiopulmonary complications of radiotherapy: 14 were due to recurrence of the malignant disease or the appearance of another tumour. Fifty-two pericardial effusion drainage procedures and 28 pericardectomies were performed, due to the necessity for reoperation. The authors have tried to determine therapeutic indications based on recognised physiopathological data and the anatomical aspects of the four different clinical forms. The prognosis is affected by post-radiotherapy fibrosis which extends beyond the pericardium to involve other cardiac structures and the pulmonary parenchyma. However, it must be emphasised that the initial survival of all these patients was due to the radiotherapy.