MENINGOCOCCAL DISEASE is primarily an invasion of the blood stream by the organism. Secondary localization occurs in such susceptible parts of the body as the meninges, followed in frequency by the lungs, the joints, the eye, the serous membranes, the testicle, and the heart. Because the cardiac complications of meningococcic disease have rarely been reported, a case of massive pericardial effusion with cardiac tamponade and associated myocarditis, which was treated with pericardial aspiration and corticosteroids, is presented. To my knowledge this is the first report of such a case treated successfully with corticosteroids. The meningococcus can involve all layers of the heart. It may produce an endocarditis occasionally associated with myocarditis. Gore1described myocarditis in 111 of 256 cases of meningococcemia observed at postmortem examination. The myocarditis was characterized by microscopic foci of interstitial and perivascular cellular infiltrations, with occasional microscopic or macroscopic abscesses and destruction of muscle fibers.