Disorders of lumbosacral (LS) facet joints are manifested by low back pain with or without referred leg pain and decreased mobility of the LS spine (LS facet syndrome). The most frequent causes of LS facet syndrome are functional disorders (functional blockade or dysfunction of facet joint=reversible restriction of facet joint movements caused by meniscoid entrapment) and degenerative changes of facet joints while the others are less frequent (spondyloarthropathies, infection, tuberculosis, synovial cyst, injury). Although it has been proven that the facet joints are one of the most frequent sources of chronic low back pain (15-45%), the fact is that the facet syndrome has been frequently overlooked in patients with chronic low back pain. Following are the main reasons for explaining why the facet syndrome has been overlooked in patients with chronic low back pain: 1. Facet joints disorders are manifested by non-specific clinical picture, 2.Diagnosis of facet syndrome cannot be established by either the conventional clinical examination or radiological examinations, 3. A very small number of doctors are practicing manual functional examination which can establish the diagnosis of facet joint dysfunction and 4. Diagnostic anesthetic block which can confirm the facet syndrome diagnosis is not a widely accessible method. There is a lack of research in frequency of facet syndrome in patients with acute low back pain. Chronic mechanical low back pain caused by dysfunction of several structurally unchanged facet joints can have the same features as the inflammatory pain which can result in misdiagnosis of spondyloarthropathy. Acute LS facet syndrome caused by dysfunction of facet joints responds very well to manual therapy. The most important therapeutic options in patients with chronic LS facet syndrome caused by degenerative changes and/or dysfunction of facet joints are manual therapy, kinesiotherapy (flexion exercises), therapeutic blocks and radiofrequency denervation. The article describes etiopathogenesis, clinical manifestations, diagnosis, differential diagnosis and therapy of LS facet syndrome with emphasis on functional disorders of facet joints that can cause particular diagnostic and therapeutic problems.