Objective: To investigate the role of Caspase-12 and ADAMTS-5 expression in chorionic villi in decidual cells in placenta previa. STUDY DESIGN: Fifteen pregnant patients with placenta previa and 15 healthy pregnant patients between 29 and 38 weeks of gestation were included in the study. Collected samples were fixed in 10% buffered formaldehyde. After routine histological follow-up, 4-6 μm thick sections were cut, and histopathological and immunohistochemical examinations were made. Results: Histopathological examinations revealed significant degeneration and apoptotic changes in syncytial cells of root villi, excessive dilation and congestion of blood vessels, and hyperplastic endothelial cells in the placenta previa group. Immunohistochemical analysis showed increased expression of ADAMTS-5 in large root villi and mature chorionic villi in the maternal region in the placenta previa group. Increased expres-sion of Caspase-12 was observed in the maternal decidual, syncytiotrophoblast, vascular endothelial, and some connective tissue cells. Conclusion: ADAMTS-5, which has anti-angiogenic and aggrecan activity, was thought to play an important role in the development of extracellular matrix development; inflammation and angiogenesis may adversely affect maternal function and development of the fetus with placenta previa and placental insufficiency. Intense Caspase-12 activity in secretory cells such as decidua cells and syncytiotrophoblast cells emphasizes the apoptotic change, efficacious in fetal development. © 2019 Science Printers and Publishers.