We have continued to study the differentiation of bone marrow derived stem cells into tissue-specific differentiated cells. We examined postmortem brains of women who received bone marrow from male relatives. In several brain regions we colocalized neuronal markers (NeuN- a neuron specific nuclear marker and Kv2.1 - a neuron specific potassium channel marker) with the human Y chromosome. In all four patients studied we detected neurons derived from the donor bone marrow. Colocalizations were confirmed using confocal microscopy. The highest number of donor derived neurons was observed in the youngest patient, a 2 year old who survived longer than the other bone marrow recipients. The finding extends our earlier findings in rodents to humans.