In patients younger than 40 years of age, especially men, ankylosing spondylitis should be highly suspected when the following symptoms occur 1. Low back pain present for several months, which may be accompanied by morning stiffness, aggravated by rest and improved by activity. 2. Asymmetric lower extremity major arthritis. 3.The presence of heel pain, plantar pain and hip pain. 4.Ocular uveitis with or without arthritis. 5.Limited anterior curvature, scoliosis and retroversion of the spine. 6.Limited thoracic extension.