Two types of psychoses with endocarditis have been described. 1. Psychoses with subacute bacterial endocarditis, terminating in death after a sudden onset of the mental symptoms. Histologic examination revealed numerous miliary abscesses and masses of cocci in capillaries of the brain cortex. This type is rarely seen in state hospitals. 2. Psychoses with chronic rheumatic endocarditis. The patients in this group may present any reaction type. Some of the cases were diagnosed as dementia præcox, other patients as manic-depressives or involutional psychoses. A 62-Year-old patient with a rheumatic infarction of the parietaloccipital region was classified as senile psychosis. The anatomical findings in the brain consisted of small or large areas of infarction, being usually the result of rheumatic-endarteritic changes. Or the brain was grossly normal, but microscopic examination disclosed numerous acellular areas, an occasional granuloma, and small connective tissue scars. In one instance a rheumatic encephalitis was present.Abstract Teaser