The authors report the case of a sixty-seven-year-old man with seronegative rheumatoid arthritis since 1967. After the treatment was discontinued, a symptomatic pericardial effusion developed during an exacerbation of rheumatoid arthritis. Histological findings suggested a rheumatoid origin. Consecutive pericardiocentesis and a concomitant adequate treatment resolved cardiac tamponade, at least during short-term follow-up. However, a long term observation will be necessary to exclude recurrent effusion or evolutive constrictive pericarditis.