Abstract： Objective To investigate the effects of transfection of heme oxygenase-1 adenovirus vector (Ad-HO-1) in vitro on hypoxia-reoxygenation injury of human liver ceils. Methods Human liver cell line L-02 cells were cultured for 24, 48 and 72 h (24-h, 48-h and 72-h groups), after adding cryopreserved Ad-HO-1. And L-02 cells were co-cultured with the adenovirus vector vehicle as controls. The HO-1 mRNA expression level of liver cells in each group was detected by reverse transcription PCR. HO-1 expression was detected by indirect immunofluorescence labeling. An inverted fluorescence microscope was applied to observe enhanced green fluorescent protein (EGFP) expression in liver cells 24 and 72 h after transfection. The liver cells in blank control group (culture for 48 h) and 48-h group were cultured for 4 h under hypoxia, followed by culture for 8 h under oxygen condition. The survival rate of cells in two groups was tested by MTT assay. Results HO-1 rnRNA expression in 24-h, 48-h and 72-h groups was significantly higher than in control group, and with the prolongation of the transfection time, HO-1 mRNA expression level was gradually increased. In blank control, 24-h, 48-h, and 72-h groups, HO-1 expression rate was 2.0%, 29%, 85.6%, and 84.6%, respectively. After hypoxia-reoxygenation culture, survival rate in blank control and 48-h groupswas (37.7±3.5)% and (89.4±5.2)% respectively (P<0.01).Conclusion Ad-HO-1 in vitro can be effectively transfected into human liver cells. The hypoxia-reoxygenation injury to liver cells with transfection was milder than that to control cells.