The analysis of the values of inflammatory parameters in the moderate (III) and severe (IV) stages of the endometriosis group versus the control group showed that concentrations of IL-1β, IL-6, hs-CRP, YKL-40, PRL and CA 125 were significantly higher in the group of patients with severe endometriosis (median values: 0.52 pg/mL, 5.98 pg/mL, 7.60 mg/L, 74.62 ng/mL, 21.81 ng/mL and 123.00 U/mL, respectively) than in the control group (p = 0.008, p < 0.001, p = 0.002, p = 0.022, p = 0.002 and p < 0.001, respectively). This evidence concerns the gene IL6 and endometriosis.