The acute low back pain is considered as a consequence of the disorganization between flexors and extensors of the body emerged as a result of wrong afferent stimulation. In definite conditions, when muscle proprioceptors send the contradictory information to the CNS, there is a possibility of the simultaneous reduction of both muscles-agonists and muscles-antagonists which can lead to the reduction of flexors of the body during lumbar extension. The authors suggest a method of treatment of acute pain syndrome in the lower part of the back by the manual relaxation of flexors of the body (muscle (m) rectus, m. obliquus abdominis, m. iliopsoas). Using this method, 119 patients with pain syndrome in the lumbar-sacral part (without symptoms of failure of function of spinal roots) first occurred less than a month ago were treated. After three sessions, the pain in the lower part of the back completely vanished in more than a third of patients (38%), significantly decreased in 48% and remained unchanged only in 14% of cases.