Ankylosing spondylitis (also known as Bechterew’s disease or Marie-Strümpell disease) is a seronegative spondyloarthropathy characterized by chronic and indolent inflammation of the axial skeleton. Severe disease can lead to fusion and rigidity of the spine. Ankylosing spondylitis is most often seen in young men and is strongly associated with HLA-B27. Patients will have progressive back pain (which improves with activity), morning stiffness, and decreased range of motion of the spine. Extra-articular manifestations include fatigue, enthesitis, anterior uveitis, restrictive lung disease, and inflammatory bowel disease. The diagnosis is based on the clinical history, physical exam, and imaging demonstrating sacroiliitis and bridging syndesmophytes. Most patients are managed with physical therapy and nonsteroidal anti-inflammatory drugs (NSAIDs). More severe cases may require tumor necrosis factor-alpha inhibitors or surgery.