In a previous description of nonbacterial thrombotic endocarditis we referred to two groups of cases which apparently had certain clinical and pathologic features in common.1The present report deals with one of these groups, which consisted of three cases of nonbacterial thrombotic endocarditis in which there was a clinical picture of thrombocytopenic purpura (fulminating in two cases), associated in one case with widespread vascular lesions. A later report will describe the second group of cases, characterized by prolonged fever, polyarthritis, inflammation of the serous membranes and vascular lesions.2 Purpuric manifestations are occasionally observed in other forms of endocarditis, particularly in bacterial endocarditis. In rheumatic fever purpura rarely occurs in a widespread, generalized form. In two of the four cases of atypical verrucous endocarditis described by Libman and Sacks3purpura was a significant symptom, and in one of them there was a reduction of the blood platelet count