Objective This study is to determinate the expression of TM4SF9 in tubal ectopic pregnancy and to explore whether the expression level of TM4SF9 at maternal-fetal interface correlated to tubal ectopic pregnancy.Materials and Methods Trophoblastic and endometrial tissues were collected from 40 tubal ectopic pregnancies, who received a diagnostic uterine curettage before laparoscopic salpingectomy.41 age-matched normal early pregnancy women, who had voluntary abortion, and 12 normally fertile women, who received an uterine sounding before IVF-ET for male infertility, were included as control groups.Immunohistochemistry was used to detect the expression of TM4SF9 in villi and endometrium.