The problems of diagnosis and treatment of Failed Back Surgery Syndrome are briefly analyzed in this article. Literature overview and analysis is supplemented by the data collected at the Spinal Neurosurgery Department in Kaunas University of Medicine Hospital during the study in which clinical findings and data were analyzed and compared to the answers of patients in the special questionnaires about pain specially designed for the patients with low back pain and the Failed Back Surgery Syndrome. During this study specially designed questionnaire was introduced for the detailed pain evaluation, McGill pain questionnaire and visual analogical scales were included in this diagnostic tool. The most important clinical aspects of diagnosis and treatment of Failed Back Surgery Syndrome are discussed in this article and compared to the clinical trial in order to point out the real their value, effectiveness and long term results. In addition, the clinical value and use of special pain questionnaires is discussed and their auxiliary role is established.