Objective To investigate the immune regulative mechanism of Leydig cells in the local infection of rat’s testis. Methods Ureaplasma Urealyticum(UU) was injected into rat’s bladder, which mimicked an ascending infectious way, and at the same time culture medium was injected into rat’s bladder as the control. The rats were sacrificed at week 1, 2 and 3 after injection respectively. Then pathological changes in testis were analyzed by histological examination. At the same time Leydig cells were separated from rat’s testis. The comparasion of levels of IL-1,IL-6,TGF-β, Fas and FasL mRNA expression among the three groups was made by RT-PCR. Results As compared with control group, the levels of IL-1, IL-6, TGF-β mRNA expression for UU supernatant and living UU groups increased; and levels of Fas and FasL mRNA expression decreased and increased respectively after UU infection. Conclusion During anti-infective immunity, rat’s Leydig cells may regulate immune function of the testis by changing the levels of IL-1, IL-6, TGF-β, Fas and FasL mRNA expression and may contribute to maintain immune privilege of the testis. Objective To investigate the immune regulative mechanism of Leydig cells in the local infection of rat’s testis. Methods Ureaplasma Urealyticum (UU) was injected into rat’s bladder, which mimicked an ascending infectious way, and at the same time culture medium was injected into rat’s bladder as The control were also sacrificed at week 1, 2 and 3 after injection respectively. Then pathological changes in testis were analyzed by histological examination. At the same time leydig cells were separated from rat’s testis. The comparasion of levels of IL- IL-6, TGF-β, Fas and FasL mRNA expression among the three groups was made by RT-PCR. Results As compared with control group, the levels of IL-1, IL- and living of UU groups increased; and levels of Fas and FasL mRNA expression decreased and increased respectively after UU infection. Conclusion During anti-infective immunity, rat’s Leydig cells may regulate immune function of the testis by changing the levels of IL-1, IL-6, TGF-β, Fas and FasL mRNA expression and may contribute to maintain immune privilege of the testis.