Neonatal nonbacterial thrombotic endocarditis (NBTE) a rare disorder yet to be diagnosed antemortem is described in 2 infants. The 1st infant was postmature and suffered from polycythemia and meconium aspiration. The meconium-stained placenta manifested evidence of ischemia and disseminated intravascular coagulation (DIC). The 2nd patient was delivered near term by cesarean section and hyaline membrane disease developed. The pathogenesis of NBTE may relate to perinatal hypoxia with transient tricuspid insufficiency, polycythemia and DIC.