Abstract: Objective To explore the effect of subchronic exposure to arsenic on sperm production and Uty gene expression in mice.Methods Forty male mice were equally divided into 4 groups randomly.The mice in group A received water alone(control), group B, C, and D received 1, 2, and 4 mg/L arsenic trioxide(As₂O₃)in drink water, respectively.After 60 days, the mice were sacrificed.The organ coefficients of testis and epididymis were determined.The sperm activity, quality, and spermatogenesis were observed.Furthermore, the expressions of Uty gene in the testis and epididymis were examined with quantitative real-time PCR(qPCR).Results The organ coefficients of testis were 3.60±0.41, 3.47±0.41, 3.15±0.46, and 3.14±0.45 and those of epididymis were 0.82±0.14, 0.80±0.12, 0.70±0.11, and 0.68±0.11 for the mice in the control, 1, 2, and 4 mg/L As₂O₃ groups, respectively.Compared with the control group, the organ coefficients of testis and epididymis in 2 and 4 mg/L As₂O₃ groups were decreased significantly(P<0.05).The sperm activity in the control group was 97%, while that in 2 and 4 mg/L As₂O₃ groups decreased to 82%and 81%, respectively(P<0.05).And the sperm malformation ratio of 4 mg/L group was 6.6%and significantly higher than that in control group(2.6%, P<0.05).The cells in the seminiferous epithelium section also decreased significantly in 4 mg/L As₂O₃ group(P<0.05).The gene expression of Uty was down-regulated significantly in testis and epididymis in both 2 and 4 mg/L As₂O₃ groups compared with the control.Conclusion Subchronic exposure to arsenic inhibits sperm production and the male reproductive toxicity induced by As may be closely related to down-regulated expression of Uty.