Fibromyalgia (FM) often occurs under the mask of non-specific low back pain (NLBP).Objective: to compare the combined disorders and treatment efficacy in FM and chronic NLBP (chNLBP).Patients and methods. We examined 33 patients with chNLBP (27 women and 6 men, mean age 51.5±16.7 years) and 53 patients with FM (47 women and 6 men, mean age 46.8±14.6 years). Pain intensity was assessed using a numerical rating scale (NRS), using the Hospital Anxiety and Depression Scale (HADS), the Screening for Somatoform Symptoms-2 (SOMS-2), the Epworth Sleepiness Scale (ESS), Insomnia Severity Index (ISI), updated Fibromyalgia Impact Questionnaire (FIQR; disability in patients with FM), Oswestry Index (IO; disability in patients with chNLBP). Comprehensive treatment of patients included educational conversations, cognitive behavioral therapy, kinesitherapy, among drugs antidepressants, and in patients with FM anticonvulsants.Results and discussion. Previously, the diagnosis of FM was established only in 15% of patients, the diagnosis of chNLBP – in 82% of patients. The intensity of pain in FM was 7.1±1.9 points according to the NRS and was higher than in chNLBP (5.6±2.4 points; p=0.002). In the group of patients with FM compared to patients with chNLBP, significantly higher values of anxiety according to HADS (10.9±4.5 and 6.9±4.0 points; p<0.001), sleepiness according to ESS (8.2±4.6 and 6.2±4.6 points; p=0.014), somatization according to SOMS-2 (28.0 and 20.0 points; p<0.001) were detected. Possible anatomical causes of pain have been identified in all patients with chNLBP and only in 13% of patients with FM. 6 months after thestart of treatment in the FM group, pain intensity significantly (p<0.001) decreased to 3.7±2.6 points according to the NRS, anxiety to 6.7±3.5 points according to HADS, depression to 4.7±2 .6 points according to HADS, disability from 54.9±18.4 to 34.0±20.2 points according to FIQR; in chNLBP group pain intensity significantly (p<0.05) decreased to 2.6±2.1 points according to the NRS, anxiety decreased to 4.2±2.5 points according to HADS, depression to 6.5±3.3 points according to HADS, disability from 37.8±17.4 to 14.5±14.2 points according to IO.Conclusion. FM is less frequently diagnosed in comparison with chNLBP, accompanied by a higher pain intensity, anxiety, sleepiness and somatization. Complex therapy leads to a stable positive effect both in chNLBP and in FM.