Lower back pain is pain that is localized in the lower back, buttocks, and sacroiliac area. Lower back pain is the most common reason for limiting physical activity in patients under 45 years of age. If we take into account both acute and chronic pain. Lower back pain is the most common complaint after colds and minor injuries. At the same time, even a thorough examination may not always reveal the cause of lower back pain. There is evidence of more frequent development of pain in the lower back on the background of benign joint hypermobility syndrome. Lower back pain in patients with benign joint hypermobility syndrome is usually assessed on the basis of visual analog scale data and is quite subjective. To assess the severity of changes in the lumbar spine, an ultrasound method can be used, one of the options of which is elastometry, which allows to determine the stiffness of the studied tissues, in particular to assess muscle tone. Muscle relaxants are commonly used for therapy, but it is usually not possible to assess their effect on actual muscle relaxation. The purpose of our study was to determine the effectiveness of using muscle relaxants in patients with lower back pain and benign joint hypermobility syndrome by performing elastometry of the iliopsoas muscles in these patients. Material and methods. To achieve this goal, we examined 65 patients with lower back pain aged 45.62±2.24 years, among them there were 32 women and 33 men. Patients with impaired limb sensitivity, muscle weakness, pelvic dysfunction, severe pain at night, fever and unmotivated weight loss, history of cancer, etc. were excluded from the study. To participate in the study, all patients underwent X-ray and ultrasound examination of the hip joints, in the presence of signs of osteoarthritis, patients were excluded from the study. Among the patients examined by the Bayton criteria, 26 patients were diagnosed with benign joint hypermobility syndrome, among them were 19 women and 7 men. We used shear wave elastometry to determine the stiffness of the distal lumbosacral muscle. A visual analog scale of pain with a gradation from 1 to 10 was used to determine the severity of the pain syndrome. After the diagnosis of lower back pain, patients were prescribed anti-inflammatory therapy in the form of 100 mg of diclofenac per day and tizanidine 4 mg 3 times a day for two weeks. After two weeks, the examination of patients was repeated. Results and discussion. In patients with lower back pain, the initial values of iliopsoas muscle stiffness were 11.85±1.37 kPa on the right and 12.1±1.45 kPa on the left, in patients with signs of benign joint hypermobility syndrome and lower back pain, the stiffness was iliopsoas muscle were 12.64±1.42 kPa on the right and 12.49±1.67 kPa on the left. No statistically significant difference was found between the studied groups. The severity of pain in the group of patients with lower back pain without benign joint hypermobility syndrome was 7.98±1.45, in patients with lower back pain and signs of benign joint hypermobility syndrome was 7.67±1.33 After 2 weeks of therapy in patients with lower back pain without signs of benign joint hypermobility syndrome, the lumbar-iliac muscle stiffness was 7.69±1.23 kPa on the right and 7.98±1.38 kPa on the left, the difference with the initial values was significant (p <0.05). In patients with signs of benign joint hypermobility syndrome and lower back pain after treatment, the lumbar-lumbar muscle stiffness was 10.29±1.97 kPa on the right and 10.89±1.75 kPa on the left. The difference was significant (p <0.05) both with the initial indicators and with the indicators of the group of patients with lower back pain without signs of benign joint hypermobility syndrome. The severity of pain on the visual analog scale in the group of patients with lower back pain without benign joint hypermobility syndrome after therapy was 3.49±1.98, in patients with lower back pain and signs of benign joint hypermobility syndrome was 5.21±1.43. The difference was significant (p <0.05) both with the initial indicators and with the indicators of the group of patients with lower back pain without signs of benign joint hypermobility syndrome and had a clear correlation with the indicators of lumbar-iliac muscle stiffness according to shear wave elastometry (r = 0.63, p = 0.032) Conclusion. Thus, the use of tizanidine in therapy can reduce the stiffness of the lumbosacral muscles of the back and reduce the intensity of pain in patients with lower back pain. At the same time, the patient's presence of benign joint hypermobility syndrome significantly reduced the degree of muscle relaxation and provoked greater resistance to pain therapy. The use of shear wave elastometry allows controling the quality of treatment in the dynamics. At the same time, there is a need to study the possibility of using this method of research in other spastic changes in the muscular system, which should be a prospect for further research