Abstract: Human liver carcinoma cell line SMMC-7721 were transfected by replication deficient retroviral vectr produced by PA317/LNC-IL-2 packaging cell line containing the interleukin-2 gene and the gene coding for resistance to neomycin (neor).This process was carried out through cocultivation. IL-2 gene was under the control of the cytomegalovirus (CMV) early promoter. After transfection the tumourcells were cultured and selected for thirty days in G418 culture medium containing G418 (400μg/ml)-a neomycin analogue toxic to eukaryotic cells. Cells which integrated with neomycin resistance gene and human interleukin-2 gene were survival.The transfection rate was 1-2%. Growth and shape of the genetically modified SMMC-7721 cells were observed.Successful gene insertion was confirmed by determining the transcription and translation of exogenous interleukin-2 gene. The result showed that the shape and growth of 7721-transduced cells had no obvious variation as compared with those of the contrlo;the biologic activity of IL-2 in the culture supernatand increased to 20-30folds more than those of the control; reverse transcriptions polymerase chain reaction (RT-PCR) showed hIL-2mRNA was obviously elevated. The study indicated that we have transferred successfully IL-2gene into human liver carcinoma cell line and obtained continuous, stable,efficient expression.