We examined whether non-hematopoietic BM cells can migrate into the intestinal graft after fetal small intestinal transplantation (FSITx). Fetal small intestine from donor C57BL/6 mice was transplanted into the rectus abdominis of recipient C57BL/6 mice with only green fluorescent protein (GFP) BM cells (syngeneic FSITx). Intestinal grafts were harvested on days 5, 10, and 30 after FSITx and stained immunohistochemically using anti-CD45 antibody (a marker for hematopoietic BM cells). Although there were no GFP-positive cells identified in the epithelium of the graft intestinal villi, there were a few cells positive for both GFP and CD45 in the lamina propria on day 5 after FSITx, and many present on days 10 and 30. In some grafts there were only cells that were GFP positive/CD45 negative (i.e., non-hematopoietic BM cells) found in the lamina propria on days 10 and 30. These data indicate that non-hematopoietic BM cells as well as hematopoietic BM cells can migrate from the recipient's bone marrow, suggesting that recipient mesenchymal stem cells may be strongly implicated in graft regeneration and development after FSITx.