We investigated 6 neonates with nonimmunologic fetal hydrops admitted to Shimane Medical University Hospital between 1979 and 1996. Chromosome analysis revealed that two of these neonates (33%) had trisomy 21 (Down syndrome). Our data may suggest the importance of chromosomal analysis of the fetus and the neonate with nonimmunologic fetal hydrops. It was revealed that each of the two neonates with Down syndrome had hematopoietic disorders including pancytopenia and transient abnormal myelopoiesis. Although nonimmunologic fetal hydrops in Down syndrome has often been attributed to the cardiac diseases, hematopoietic disorders should also be considered to be a cause of the fetal hydrops in Down syndrome.