Mesenchymal stem cells (MSCs) in human umbilical cord blood are multipotent stem cells that differ from hematopoietic stem cells. They can differentiate in vitro into mesenchymal cells such as osteoblasts and adipocytes. However, differentiation into nonmesenchymal cells has not been demonstrated. Here, we report the isolation, purification, expansion, and differentiation of human umbilical cord blood MSCs into neurocytes in vitro. Cord blood samples were allowed to drain from the end of the cord into glass bottles with 20 U/mL preservative-free heparin. MSCs were isolated from human umbilical cord blood, purified, and expanded in Mesencult medium. Surface antigens of MSCs were analyzed by fluorescence-activated cell sorting (FACS). MSC passages 2,5, and 8 were induced to differentiate into neuron-like cells. Neurofilament (NF) and neuron-specific enolase (NSE) were detected by immunohistochemistry staining. Special Nissl bodies were observed by histochemical analysis. The results showed that 6.6 × 105 primary MSCs were expanded for 10 passages to obtain 9.9 × 108 MSCs, an increase of approximately 1.5 × 103-fold. FACS results showed that the MSCs did not express antigens CD34, CD11a, and CD11b and expressed CD29 and CD71, an expression pattern identical to that of human bone marrow-derived MSCs. Induction results indicated that approximately 70% of the cells exhibited a typical neuron-like phenotype. Immunohistochemistry staining suggested that induced MSCs of different passages expressed NF and NSE. Special Nissl bodies were obvious in the neuron-like cells. These results suggest that MSCs in human umbilical cord blood are capable of differentiating into neuron-like cells in vitro.Int J Hematol. 2003;78:256-261.