Abstract: Objective To investigate the effect of epithelial cells on the cyclin I expression of stromal cells in benign prostatic hyperplasia(BPH).Methods The stromal-epithelial co-cultured model was constructed after prostate epithelial cells and stromal cells were separated and identified from the tissue of benign prostatic hyperplasia with cell morphology and immunohistochemistry.The expression of cyclin I mRNA in stromal cells with or without the epithelial cells co-cultured was detected with reverse transcription PCR(RT-PCR).Results The prostate-specific antigen(PSA) was only detected in epithelial cell,and desmin was only detected in stromal cells.After the stromal-epithelial co-cultured model was constructed,the expression of cyclin I was detected.Cyclin I mRNA was lower in stromal cells with epithelial cells co-cultured than that in stromal cells without epithelial cells co-cultured.The ratio of gray level between cyclin I to glycerol-3-phosphate dehyclrogenase(G3PDH) in stromal cells with or without epithelial cells co-cultured was 1.001±0.29 and 1.117±0.31(P< 0.05).Conclusion The epithelial cells can suppress cyclin I expression in stromal cells in BPH.