Several lines of evidence indicate that immunologic effectors, particularly suppressor T cells and NK cells, may play a task within the pathogenesis of idiopathic repetitive abortions. to research the involvement of those immune cell populations, we determined the immunophenotypic characteristics of endometrial leukocytes from nonpregnant recurrent aborters. Habitual aborters with a negative investigation underwent an endometrial biopsy during their luteal phase and were followed prospectively to assess clinical outcome. Endometrial leukocytes were evaluated by two-color flow cytometric analysis. the share of endometrial CD8+ T lymphocytes was significantly decreased in recurrent aborters, and their CD4:CD8 ratio was increased. In contrast, the proportion of B lymphocytes (CD20+) was strikingly increased in these patients' endometria.