A case of May-Hegglin anomaly, a rare autosomal dominant thrombocytopenia, is reported. This disorder is characterized by giant platelets, basophilic inclusion bodies within the cytoplasm of granulocytes and an occasional bleeding tendency. This bleeding tendency depends on the platelet count. The fetuses of such patients run the risk of intracranial hemorrhage in utero and during the early neonatal period following vaginal delivery. Prenatal diagnosis of this disorder has not yet been reported. We describe a case of this disorder, diagnosed in pregnancy, which, following prenatal diagnosis of mild thrombocytopenia in the fetus and confirmation by cordocentesis, could successfully undergo a vaginal delivery.