Objective To study the effects of genistein on the biological characteristics of and collagen synthesis by human skin fibroblasts in vitro.Methods Human skin fibroblasts(HSFBs)were obtained from the prepuce of healthy adolescents,and suhjected to primary culture.Atier 5 to 15 passages of culture,HSFBs were treated with various concentmtions(0.03125,0.0625,0.125,0.25,0.5,1mg/L)of genistein for different durations.The potential of cell proliferation was detected by MTT assay and growth curves were drawn for HSFBs.Flow cytometry(FCM)and RT-PCR were used to estimate cell cycle phases and mRNA expression of type Ⅰ procollagen.respectively.Results The proliferation rate of HSFBs was 97.7%,113.8%,132.5%,116.4%,94.5%and 83.3%after treatment with genistein of 0.03125,0.0625,0.125,0.25,0.5 and 1 mg/L,respectively.The genistein of more than 0.5 mg/L displayed an inhibitive effect on the proliferation of HSFBs.while that between 0.0625 and 0.25 mg/L showed a promotive effect.Atier treatment with genistein at 0.0625,0.1 25 and 0.25 mg/L,the percentage of HSFBs in S phase and G2 phase significantly increased compared with untreated HSFBs(S phase:41.15%±2.88%,61.89%±3.16%,48.18%±1.68%vs30.12%±0.60%,P＜0.05;G2 phase:9.76%±3.99%,10.40%±0.54%,7.46%±2.47%vs 0.61%±0.16%,P＜0.05).Compared with the untreated HSFBs.the relative mRNA expression level of type Ⅰ procollagen was increased with genistein of 0.0625,0.125 and 0.25 mg/L(0.4814±0.0138,0.5767±0.0291,0.5675±0.0272 vs 0.4101±0.0236,P＜0.01),but decreased with genistein of Ⅰ and 0.5 mg/L(0.1662±0.0165 and 0.2017±0.0203 vs 0.4101±0.0236,P＜0.01).ConclusionCertain concentrations of genistein could enhance the proliferation and growth of as well as mRNA expression of type Ⅰ procollagen in HSFBs.