It has been proposed that endometriosis development is associated with autoimmune disorders. The aim of this study is to elucidate the type of B-cell differentiation and autoantibody production at the systemic and local levels in women with different stages of endometriosis and infertility. 35 women with stages I-II of endometriosis, 25 women with stages III-IV of endometriosis and 25 gynecologically healthy women (control group) were recruited into the study. B-lymphocyte phenotype was assessed using three-color flow cytometry and concentration of anti-ovary and anti-Zona Pellicida (ZP) autoantibodies was measured using enzyme-linked immunosorbent assay (ELISA). It was found that all women with endometriosis were characterized by low level of switched memory CD19+IgD-CD27+ B-cells, high level of unswitched naïve CD19+IgD+CD27- B-lymphocytes and elevated number of plasma cells in peripheral blood and peritoneal fluid in comparison to the control group. In the peritoneal fluid of all women with endometriosis the amount of unswitched memory CD19+IgD+CD27+ B-cells was increased. Changes at the local level were significantly more pronounced in the group of women with severe endometriosis than in the group with mild endometriosis. In women with stages I-II of endometriosis we noted the elevation of serum content of anti-ZP and anti-ovary antibodies, whereas women with stages III-IV of endometriosis were characterized by higher level of anti-ovary antibodies both at the systemic and local levels. But in all cases the concentrations of autoantibodies were lower compared to that in persons with true autoimmune disorders. It could be concluded that endometriosis development is associated with increased autoreactivity but not with true autoimmunity.