To explore the efficacy of the different combinations of stem cell factor (SCF), FLT3 ligand (FL) and interleukin (IL) 2, 7, 15 on the induction and expansion of cord blood (CB) derived CIK/ NK cells in vitro, according to the different combinations of cytokines, combinations of cytokines were divided into 3 groups: group A (SCF + IL2 + IL7 + IL15), group B (SCF + FL + IL2 + IL7 + IL15) and group C (IL2 + IL7 + IL15 as control group). At 21 days of culture, the proportion and the expansion rate of CD3(+)CD56(+) CIK cells and CD3(-)CD56(+) NK cells were measured. The results showed that at 21 days in culture, the percentages of CD3(+)CD56(+) CIK cells derived from CB-MNC in group A, B and C were (19.84 +/- 2.93)%, (26.20 +/- 4.05)%, (24.03 +/- 4.99%) and that of NK cells were (49.60 +/- 1.40)%, (51.16 +/- 6.45)% and (30.85 +/- 8.12)%, respectively. The proliferation of CD3(+)CD56(+) CIK cells and CD3(-)CD56(+) NK cells was the most effective in group B (SCF + FL + IL2 + IL7 + IL15). Expansion multiple of CIK cell number increased from 575.81 +/- 221.72 (control) to 796.09 +/- 278.47 with peak value of 1 313, and that of NK cells increased from 30.39 +/- 14.47 (control) to 65.85 +/- 30.83 with peak value of 121.06. In conclusion, a proper cytokines (SCF + FL + IL2 + IL7 + IL15) culture system can effectively induce and expand CB CD3(+)CD56(+) CIK cells and CD3(-)CD56(+) NK cells simultaneously.