Electron microscopic examination of peripheral blood of women with placental failure of different origin showed specific features of cells and noncellular components: high contact activity, phagocytic activity, highly active B-lymphocytes (plasma cells), cytolysis, cytoplasm clasmatosis, small segmentation of neutrophil nuclei, high concentration of non-cellular components presenting as ultramicrogranules and fibrils, cell fragments, membranese, and granules, and atypical blood components (fibrinoid structures bacteria, and virus-like particles). These data can be used for selecting optimal simple tests for diagnosis and treatment monitoring.