Recently it was reported that chorionic villous hemorrhage (CVH) had a significant association with retroplacental hemorrhage (RPH). In this study, to determine whether CVH has a correlation with RPH or intervillous thrombosis (IVT), placentas associated with CVH were clinico-histopathologically investigated and compared to those with IVT. Obstetric complications in 32 cases with CVH were compared with 258 cases with IVT. Placental abruption was significantly higher (18.7%) in the CVH group than in the IVT group (5.03%) and the incidences of intrauterine fetal death (IUFD) as well as intrauterine growth retardation (IUGR) were also significantly higher (18.7% and 9.37%) in the CVH group than in the IVT group (3.10% and 2.32%). Of the pathological characteristics of the placentas with CVH, IVT was found in 46.8%, but marginal or retroplacental hemorrhages were seen in 34.3%, compared to 14.2% of the IVT group. Premature infants with low birth weight (under 2000 g) and before 36 weeks of gestation were born in 53.1% and 34.3% of cases with CVH placentas. CVH was not only located near the basal plate of the placentas and decidual hemorrhages, but was also highly associated with chorangiosis in 75% of cases. Using histological and ultrastructural studies in CVH cases, villous stroma was filled with fetal erythrocytes and leakage of blood cells was observed through a disruption of the trophoblast layer of hemorrhagic villi. In conclusion, it is suggested that CVH may rather be related to formation of the intervillous thrombosis than to RPH.