Abstract: 2000 biopsy and 60 outopsy placentus were examinated under light microscope and cli-nical statistical data were recorded.100 cases of chorioangiosis were discovered and indica-ted.The chorioangiosis is associated with villitis.The inflammatory cells infitrate in villose mesenchyme and placental vascular proliferation may be caused.Acute and chronic ischemic changes of placente may also lead to chorioangiosis.Chorioangiosis results from cesarean sec-tion.It is important that chorioangiosis may cause fetal distress,intrauterine growth retarda-tion,abnormality and death of the neonate and fetus.

Key words: chorioangiosis, pathobiology, etiology