Objective To investigate the function of HOXa-10 gene in the course of mouse blastocyst implantation. Methods Real-time fluorescence quantitative PCR was applied to detect the expression of HOXa-10 gene in normal mice and day1, day2, day3 day4,day5 and day7 pregnant mice. Plasmid containing the HOXa-10 cDNA fragment with liposome and plasmid containing HOXa-10 antisense oligonucleotides with liposome were transfected respectively into the uterine horns of day 2 pregnant mice, and the number of blastocyst implanted was counted and compared with that of normal day 2 pregnant mouse. Results HOXa-10 gene expression in the pregnant group is higher than that of the nonpregnant group, and the results showed a gradual increasing trend as days went by: HOXa-10 gene expression was the highest on pregnancy d4，began descending on pregnancy d5 and was close to that of non_pregnancy on pregnancy d7. The number of blastocyst increased in the uterine horns which were injected with plasmid containing the HOXa-10 cDNA fragment with liposome. On the contrary, the number of blastocyst decreased in the uterine horns which were injected with plasmid containing HOXa-10 antisense oligonucleotides with liposome(P<0.05).Conclusion HOXa-10 gene is persistently expressed in mice endometrium during early pregnancy and may participate in the regulation process of mouse blastodyst i