According to the power analyzes 32 patients, who were diagnosed as Ankylosing spondylitis, will be taken to the study. In the first session their spinal mobility, flexibility, dynamic and static balance, back and lower limb muscle strength, pulmonary functions and pulmonary muscle strength, disease activity level, fatigue level, functional exercise capacity will be assessed to determine functional status by a physiotherapist. Also their quality of life and factors affecting the quality will be assessed. Then the patients will be divided into two exercise groups randomly. Patients in the first group will only do aerobic exercise, patients in the second group will do clinical pilates additional to the aerobic exercise which has the same protocol with the first group. Patients will do the exercise for 8 weeks, 3 times a day individually with a physiotherapist . At the end of the 8 weeks they will be assessed with the same tests again.