Summary: Recurrent spontaneous abortion is an obstetric complication with undefined causes. Apoptosis, proliferation, and adhesion are considered important factors in the pathogenesis of abortion. This work aimed to determine Bax and Bcl-2 as a proapoptotic and antiapoptotic protein, Ki67 and P27kip as proliferative and antiproliferative proteins, and E-cadherin and CD44 as adhesion molecules in the trophoblastic tissues in cases with recurrent miscarriage. Immunohistochemistry and quantitative polymerase chain reaction analysis of Bax, Bcl-2, Ki67, P27kip, E-cadherin, and CD44 in paraffinembedded sections of placental tissues obtained from 108 women were divided into 3 categories: 66 Toxoplasma gondii–positive women with recurrent abortion, 22 T. gondii–negative women with recurrent abortion, and 20 women with no history of abortion as a control group. The mean ratio of the expression of Bax and P27kip proteins was 35.3% and 36.1%, which is significantly higher than that of the second group (19.88 and 20.02%), and the third group (12.3% and 10.98%), while the mean ratio of the expression of Bcl-2, Ki67, E-cadherin, and CD44 proteins was 12.35%, 11.23%, 10.32%, and 9.97%, which is significantly lower than that of the second group (33.75%, 13.18%, 21.88%, and 23.29%) and that of the third group (38.58%, 39.27%, 37.98%, and 35.79%). The presence of proapoptotic protein (Bax) and antiproliferative protein (P27kip) at high levels and the presence of antiapoptotic protein (Bcl-2), proliferative protein (Ki67), and adhesion molecules (E-cadherin and CD44) in lower levels in the T. gondii–positive group clarify the mechanism involved in the induction of abortion and loss of pregnancy. Key Words: Apoptosis—Proliferation—Adhesion—RSA—Toxoplasma gondii.