The investigators estimated the blood concentrations of cytokines (IL-6, IL-8, IL-10, TNF-α), α2-macroglobulin (MG), α1-antitrypsin, pregnancy-associated α2-glycoprotein (PAG), lactoferrin (LF), and immune complexes (MG IgG, PAG IgG) in 69 patients with Stages III-IV external genital endometriosis (who took and did not take gonadotropin-releasing hormone agonists (GnRH-A)) before and 3-6 months after surgery. Before surgery, the patients with external genital endometriosis had higher LF and lower MG of all the above blood parameters. The levels of MG and LF became normal and the content of PAG IgG increased after combination treatment (surgery + GnRH-A therapy). Within a year after the combination treatment, the symptoms of endometriosis were abolished in 96% of the women, reproductive function was recovered in 30.4% of cases, and 4.3% of the women developed a recurrence of the disease.