Abstract: Objective To investigate the protective effect of metallothionein(MT) on testicular injury in mice with nickel-chromium(NiCr)-combined exposure.Methods Fifty Kunming mice were randomly divided into five groups based on weight:control group, NiCr-combined exposure group, low, moderate, and high dose MT group.The mice in solvent control group were given normal saline intragastrically.The mice in NiCr-combined exposure group were given 1.0 mg/kg·bW nickel sulfate and 0.5 mg/kg·bW potassium dichromate solution.The mice in low, moderate and high dose MT groups were given 5.0, 10.0 and 15.0 mg/kg·bW MT solution intragastrically.The mice in NiCr-combined exposure group and MT groups were given nickel sulfate-potassium dichromate combined solution intragastically in the morning, and then were given MT solution intragastically in the afternoon.All the mice had the intragastic administration once a day for 20 days.At the end of the treatments, all mice were sacrificed and their blood samples were collected, and the testis and epididymis viscera coefficients were measured.The testicular pathological morphology and sperm quality were observed.Apoptosis of testicular cells and content of superoxide dismutase(SOD) and malondialdehyde(MDA) were detected.Results The testis and epididymis viscera coefficients(0.73%, 0.24%) were reduced in the mice with NiCr-combined exposure, but the mice in moderate and high dose MT groccp showed repairment of impaired testicular structure and increased testis viscera coefficient(1.13%, 1.25%) and epididymis viscera coefficient(0.37%, 0.39%)(P<0.05 for all).Compared with NiCr-combined exposure group, the mice in moderate and high dose MT group had improved sperm counts(17.25×10⁷/g, 17.79×10⁷/g) and energy(68.25%, 70.48%), reduced ratio of abnormal sperms(6.55%, 4.77%), improved testis SOD activity(298.26, 313.19 U/gProt), and reduced apoptosis rate(9.57%, 9.02%) and MDA content(28.16%, 25.55%)(P<0.05 for all).Conclusion MT has protective effect on testicular injury in mice with nickel-chromium-combined exposure and the mechanism of the protective effect may be correlated with improvement of enzyme activity, reduction of testicular cells apoptosis, and enhancement of antioxidant effect.