The purpose of the study was to observe the effect of rapamycin (RAPA) on the differentiation and maturation of rat bone marrow-derived dendritic cells (BMDCs) in vitro. BMDCs from Wistar rats were cultured with granulocyte-macrophage colony-stimulating factor plus interleukin-4in the presence or absence of RAPA (20 ng/mL), and stimulated with lipopolysaccharide (LPS) for 24h before cells and supernatants were collected. Surface phenotype of BMDCs was flow-cytometrically detected to determine the expression of maturation markers, MHC class Ⅱ and CD86. Supematants were analyzed for the production of IL-12 and IFN-γ cytokines by using ELISA.BMDCs were co-cultured with T cells from Lewis rats and mixed lymphocyte reaction was assessed by MTT method. The morphology of BMDCs stimulated with LPS remained immature after RAPA pretreatment. RAPA significantly decreased the CD86 expression, impaired the IL-12 and IFN-γproduction of BMDCs stimulated with LPS, and inhibited the proliferation of allogeneic T cells. In conclusion, RAPA can inhibit the maturation of BMDCs stimulated with LPS in terms of the morphology, surface phenotype, cytokine production, and ability of BMDCs to stimulate the proliferation of allogeneic T cells in vitro.