Japanese herbal medicines (Kampo medicines) are usually the third most popular choice among medicines for treatment of endo­metriosis in Japan. This traditional therapy is used to improve various signs and symptoms of endometriosis without decreasing serum estradiol levels or causing menstrual disorders. We used flow cytometry to examine and compare the effects of the Kampo therapy and danazol on anti-endometrial humoral immunity. Autoantibodies against endometrial epithelial cell lines and endome­trial stromal cells were detectable in all the examined sera of men and women irrespective of the presence of endometriosis. Moreo­ver, no significant increase in anti-endometrial antibodies was found in endometriotic patients. Anti-endometrial antibodies included Ig-γ chain, lg-µ chain, Ig-κ chain, and lg-λ chain indicating polyclonal B cell activation in the endometriotic patients. Absorption tests of nonspecific antibodies with cervical cancer cells or ovarian cancer cells revealed that endometriotic patients had higher levels of endometrium-specific autoantibodies than did non-endometriotic healthy women. IgM fractions from endometriotic patients and healthy women differed in their effect on growth of endometrial adenocarcinoma cells. Therapy with the herbal com­pounds Keishi-bukuryo-gan but not danazol therapy, gradually decreased the tissue-specific anti-endometrial IgM antibody levels. These results indicate that tissue-specific anti-endometrial IgM may be a useful therapeutic marker for endometriotic patients treated with Keishi-bukuryo-gan and that endometrial tissue-specific immune disorders play specific roles in the pathogenesis or develop­ment of endometriosis.