This study aims to determine how the expression of osteopontin is altered in the placenta percreta by compar-ing osteopontin expression in normal placentas and placenta percreta tissues.Placental tissues from hysterectomy materials which were histopathologically diagnosed with placenta percreta (study group, n = 20) and placental tissues obtained from normal term pregnancies (control group, n = 20) were immunohistochemically stained with osteopontin antibody. The groups were compared with respect to the intensity of cytoplasmic staining for osteopontin.The study and control groups were similar with respect to age, gravidity, parity, gestational age at birth, number of previous cesarean deliveries and curettages and (p > 0.05 for all). Immediate postoperative hemoglobin was significantly lower and the need for blood transfusion was significantly higher in the study group (p = 0.001 for both). Placental osteo-pontin expression was significantly altered in the study group (p = 0.020). Negative staining for placental osteopontin was significantly more frequent in the placenta percreta group than the control group (9/20 vs 0/20, 45.0% vs 0%, p = 0.037).As reduced placental osteopontin expression was determined in the placenta percreta cases compared to the normal term placenta tissues, osteopontin can be considered to have a role in morbidly adherent placentation. This study is of value as the first study to investigate the changes in osteopontin expression in placenta percreta cases.