To construct a prokaryotic expression system to serially express Alloferon-1 and to determine the anti-tumor activity of its products in vitro.An artificial fusion gene containing 6 x His-EK-8 x Alloferon-1-EK-6 x His sequences was constructed by linking primer PCR. By using routine molecular biological methods, the artificial fusion gene was cloned and its prokaryotic expression system was then constructed. SDS-PAGE and BioRad Agarose Image Analysor was applied to measure the expression and output of the target recombinant products 8 x rAlloferon-1-EK. Ni-NTA affinity chromatography and EK digestion and Sephadex G-50 chromatography were performed to extract 8 x rAlloferon-1-EK and rAlloferon-1-EK, respectively. The proliferation of KB, SGC and HL-60 tumor cells was tested by using MTT method after treatment with directly synthesized Alloferon-1 (sAlloferon-1), Aloferon-1-EK (sAlloferon-1-EK) and rAlloferon-1-EK.The target artificial fusion gene and its prokaryotic expression system pET42a-8 x rAlloferon-1-EK-E. coliBLDE3 with the expected sequences were obtained. Under inducement of IPTG, the prokaryotic expression system expressed the target serial recombinant protein 8 x rAlloferon-1-EK and its output was approximate 30 % of the total bacterial proteins. 8 x rAlloferon-1-EK and rAlloferon-1-EK were obtained through Ni-NTA and Sephadex G-50 columns. sAlloferon-1, sAlloferon-1-EK and rAlloferon-1ìrAlloferon-EK showed similar remarkable effects of inhibiting the growth and proliferation of KB, SGC and HL-60 cells in vitro within 25 approximately 100 microg/ml concentration range (P0.05).A prokaryotic expression system to serially express rAlloferon-1 has been successfully constructed. The product rAlloferon-1-EK has a similar anti-tumor activity compared to both the synthesized Alloferon-1 and Alloferon-1-EK in vitro.