In 25 cases of pregnancy complicated by SLE, we examined the relationships between fetal growth and histopathological findings in the placental villi. The following results were obtained. 1. As for histological findings in the placenta, in most cases clear findings of circulatory disorders were obtained. 2. In the light microscopic visual field at x63, no difference was observed among the group in the cross section occupying rate of the villi and cross section area of the terminal villi, but in one case in the IUFD group, the villi were underdeveloped and the cross section occupying rate of the villi was low. 3. The villous/vascular cross section area ratio per single terminal villus became smaller in the following order: full term AFD group, full term SFD group, premature AFD group, and premature SFD group, and a significant difference was observed between the normal controls and the premature SFD group. 4. During immunoglobulin staining by the PAP method, IgG deposits were observed in the villous syncytiotrophoblasts and their periphery, in vascular endothelial cells in the villi, and in the villous interstitium, etc. in both the SLE cases and the normal controls, but deposits of IgM in the same regions were observed only in the premature SFD group of pregnancies complicated by SLE.