Objective. To compare immunochemical and clinical parameters in patients with chronic radicular and myofascial back pain. Material and methods. A study included 92 patients (55 men and 37 women) with radicular pain syndrome and 97 patients (33 men and 64 women) with myofascial pain syndrome. Pain status was assessed with the differential visual analogous scale (at rest, on movement, at night and during spontaneous pain). Tensor algometry was used to measure pain intolerance thresholds at day and night. Levels of natural antibodies (nAB) to endogenous pain regulators (β-endorphin, orphanin, serotonin, dopamine, histamine and angiotensin) were determined in the blood serum by ELISA. Patients were examined at admission to the hospital, on 10th and 21st days of treatment. Results and conclusion. There was a significant decrease in pain syndrome in all patients to the 21st day. Pain intensity was higher in patients with radicular pain syndrome (р<0.05) in all functional states. Pain intolerance thresholds were initially reduced in both groups. No significant between-group differences in the dynamics were not found either in men or women. Women had lower pain intolerance thresholds compared to men. An analysis of nAB profiles to pain regulators showed that they were correlated with higher and high indices, with the predominance of nAB to β-endorphin, orphanin and histamine in both groups. The increased levels of antibodies circulate in the blood serum of patients with dorsalgia for a long time can further be a factor of pain chronification.