A 16-month-old boy who presented with bruising, anemia, an abdominal mass, thrombocytopenia, and afibrinogenemia was cured by the surgical removal of a large splenic hemangioma. Preoperatively, coagulation studies revealed low normal levels of Factors V and VIII, normal fibrinolysis, and high levels of immunologically detectable split products of fibrinogen. The half-life of 131I-labeled fibrinogen was 36 hours preoperatively and 72 hours postoperatively. Thirteen other cases of hemangioma and thrombocytopenia (Kasabach-Merritt syndrome) associated with hypofibrinogenemia are reviewed. © 1968 The C. V. Mosby Company.