For many years pathologists have recognized a form of pericarditis which afflicts patients who are dying of debilitating diseases, but which does not appear to be concerned in their deaths. This has been designated "terminal pericarditis." In considering pericarditis we have attempted to separate our material into groups conforming to pathologic and clinical criteria, so that comparative study would be possible. We appreciate the fact that separation into clearcut types is often difficult, and that some degree of overlapping may occur. We have attempted to show that fibrinous pericarditis without effusion is the simplest form of pericarditis, but have stated that it usually is the forerunner of purulent or of nonpurulent pericarditis with effusion, and of adherent pericarditis. The accurate segregation of cases of so-called terminal pericarditis is obviously difficult, for it is possible to include cases of fibrinous pericarditis. In order to minimize the possibility of error, we selected,