Marantic or nonbacterial thrombotic endocarditis (NBTE) associated with systemic embolism is usually a complication of advanced or terminal malignancies. We report on the case of a 46-year-old woman in whom nonbacterial thrombotic endocarditis (NBTE)-related cerebral embolism was the first clinical sign of ovarian neoplasm, which was diagnosed after cardiac surgery. Marantic endocarditis should alert the physician to make every effort to diagnose the possible background of this clinical phenomenon. Early identification of NBTE, treatment of the underlying disease, and the associated coagulopathy could possibly prevent cardiac surgery.