Endocarditis due to fungi is an exceedingly rare clinical entity. Joachim and Polayes1described a case of subacute endocarditis with systemic mycosis (moniliasis) in a drug addict and referred to another case in which autopsy revealed evidence of mycotic endocarditis. The following case, also in a drug addict, is similar in many respects to that of Joachim and Polayes and is considered worthy of reporting because of its apparent rarity, and because of its possible public health importance, since these cases occurred in drug addicts. A white man aged 49 was admitted to the United States Public Health Service Hospital on May 11, 1940 for treatment of drug addiction (heroin) which dated from 1914. His previous medical and personal history showed nothing relevant to the present report. Physical examination on admission was negative except for many missing and some artificial teeth, defective vision and hemorrhoids. Serologic tests for syphilis