Fibrinous pericarditis without effusion is undoubtedly the most common disease of the pericardium. It is the forerunner of many cases of pericarditis with effusion, of purulent pericarditis, and of adherent pericarditis. The uncomplicated form of this disease is probably the most innocuous form of pericarditis. The inflammatory process may involve either the visceral or the parietal layers of the pericardium, or both, and may be localized or widespread in its involvement. A fibrinous exudate occurs, which, when the deposition is marked, results in the "shaggy" or "bread and butter" appearance of the pericardium. MATERIAL Fibrinous pericarditis without effusion occurred in sixty-two of 373 cases of pericarditis, an incidence of 16.6 per cent. These cases occurred in forty-three males (69.4 per cent) and nineteen females (30.6 per cent). It is interesting to observe that the incidence of cases of pericarditis of all groups in males is predominant. The reason for this