The objective of the work was to make a comparative analysis of the result of external genital endometriosis treatment with the use of traditional surgical intervention and hormone therapy together with the use of low-molecular-weight metabolic immune response modifier 5-amino-1,2,3,4-tetrahydrophthalazine-1,4-dione of sodium salt. Materials and methods: the experimental part of the study was previously conducted on 50 female rats which consisted of studying the influence of the immune response modifier on the course of experimentally induced endometriosis in experimental animals, in particular on changes in the estrous cycle. Injection of the immune response modifier caused retrogression of endometrioid heterotopias and normalization of the estrous cycle in the animals. The comparative analysis of the results of external genital endometriosis treatment in 66 women was conducted on the basis of experimental research. 34 women, apart from surgical intervention and hormone therapy, were injected with the immune response modifier 5-amino-1,2,3,4-tetrahydrophthalazine-1,4-dione of sodium salt during the post surgical period. Cellular immunity, T- and B-lymphocytes, and equipment and instrumental methods, such as medical ultrasound of the organs of the lower pelvis and laparoscopy, were used to assess the results of treatment. As a result of the treatment with the use of the immune response modifier the indicators of cells immunity changed, pain severity decreased, menstrual function normalized, relapse frequency reduced, and the overall quality of life for patients improved. Socially significant effect of treatment of external genital endometriosis using metabolic immune response modifier is manifested in implementation of reproductive function ‒ elimination of infertility in 50 % of women during the first year of observation.