Abstract: Objective To observe the effects of recombinant Sagartia rosea cytolysin (rSrc) and Lapemis hardwickii phospholipase A₂(rPLA₂) on adventitial fibroblasts proliferation. Methods NIH-3T3 cells were cultured and treated with rSrc and rPLA₂ at different concentrations for observation of cell proliferation using non-radioactive MTS/PES assay in comparison with the control group. Results The ratio of cell proliferation was 0.840±0.061 in the control group, and was 0.263±0.044, 0.418±0.054, 0.605±0.063, 0.772±0.054 and 0.906±0.072 in rSrc groups corresponding to rSrc concentrations of 100, 10, 1 μg/ml and 100, 10 ng/ml respectively. rSrc was found to significantly inhibit fibroblast proliferation in a dose-dependent manner when the concentration used was above 1 μg/ml (P<0.05), as compared with the control group (P<0.05). The ratio of cell proliferation was 0.498±0.076, 0.937±0.112 and 0.978±0.145 in rPLA₂ groups corresponding to rPLA₂ concentrations of 100, 10, 1 μg/ml respectively, indicating that rPLA₂ also significantly inhibited fibroblast proliferation at the concentration of 100 μg/ml (P<0.05). Conclusion rSrc and rPLA₂ can both significantly inhibit adventitial fibroblast proliferation.