Abstract: Objective To study the expressions of the members of HSP110 family in the testis and epididymis of mice at different stages of development and whether they are regulated by hormones. Methods The testicular and epididymis tissues of mice at different ages (14, 21, 28, 35, 42, 49, 70, and 90 days after birth, 3 mice at each age) were collected for RT-PCR detection of the expression levels of HSP110 family members. Forty-eight mice were randomized into 3 groups for sham operation, castration, or castration with testosterone injections every other day (starting at 7 days after castration), and at 1, 3, 5, and 7 days after first testosterone injection, the expressions of HSP110 family in the epididymis were detected using RT-PCR. Results The mRNA expression levels of HSP110 family members underwent obvious variations with the development of the mice: HSPA4, HSPA4l and HSPH1 expressions in the testicles of the mice first increased and then decreased, and gradually became stable; they also exhibited similar temporal patterns of changes in the epididymis. In the castrated mice, the mRNA expressions of HSPA4 and HSPA4l in the epididymis decreased significantly with the reduction of serum hormone levels (P<0.05), and became normal after the supplementation of exogenous hormone. Conclusion The expression levels of HSP110 family are affected by developmental regulation, and the expressions of HSPA4 and HSPA4l are under the regulation by hormones.