In order to clarify the significance of rheumatoid arthritis (RA) as a cause of cardiac compression, we scrutinized pericardiectomy files of 47 patients over a ten-year period at two university hospitals in Finland. Five patients with RA were found. All the patients with RA were men with seropositive disease and subcutaneous rheumatoid nodules. Two of the patients had pulmonary fibrosis, one had cutaneous vasculitis and three had had rheumatoid pleurisy. There was a mean delay of 10 months from the first cardiac symptom to the diagnosis of cardiac compression, the most common misdiagnosis being primarily a liver disease. On the basis of clinical and operative data, four out of the five patients had constrictive pericarditis and one had an effusive-constrictive form of the disease. The histopathological findings in all cases were consistent with chronic fibrosing pericarditis. A follow-up of seven to seventeen years of four patients has not revealed any signs of recurrent pericardial disease. Our results demonstrate that RA is an important aetiological factor for cardiac compression. The long-term outcome of this manifestation seems to be good after pericardiectomy.