To compare the expansion efficiency and function of dendritic cells derived from CB-CD34+ cells and MPB-CD34+ cells by using two-step culture method, enriched CB-CD34+ cells or MPB-CD34+ cells with immunoadsorption were primarily cultured in the presence of FL, SCF, TPO, GM-CSF for 10 days, and then further cultured with a combination of GM-CSF, IL-4, TNF-alpha, CD40Ab and PGE2 to induce DC. The DC phenotypes were detected by flow cytometry, the expansion efficiency and cell function were evaluated by mix-lymphocyte reaction (MLR), IL-12 level was detected by using ELISA and the chemotactic function mediated by secondary lymphoid tissue chemokine (SLC) was determined with Transwell plate. The results indicated that after 10 days of expansion, there were no significant difference in the percentage of CD14+CD1a- cells between CB and MPB [(40.48 +/- 16.85)% vs (28.07 +/- 23.19)%, P > 0.05], but the expansion of total cells in CB was higher than that in MPB (388.88 +/- 84.63-fold vs 79.67 +/- 10.32-fold, P < 0.01), so the yield of CD14+CD1a- cells from CB was significantly higher than that from MPB too (189.42 +/- 25.02-fold vs 28.74 +/- 23.27-fold, P < 0.01). The percentage of CD83+ DCs cultured with CD40Ab/PGE2 derived from CB were higher than those cultured with TNF-alpha derived from MPB respectively [(34.52 +/- 11.22)% vs (3.70 +/- 2.27)% and (36.69 +/- 13.36)% vs (7.34 +/- 3.364)% respectively, P < 0.01]. In the same circumstance, the yield of CD83+ DCs derived from CB was much more than that from MPB (198.72 +/- 117.53 times vs 33.95 +/- 6.19 times, P < 0.01). There were no difference in stimulating capacity, IL-12 secretion and migration capacity between DCs derived from CB and MPB. It is concluded that DCs induced from CB-CD34+ cells by two-step culture possess similar functions with that from MPB-CD34+ cells, but the yield of DCs from CB CD34+ cells is much more than that from MPB CD34+ cells.