Quality of life encompasses the net effects that a patient perceives an illness to have on his or her life. Quality of life commonly includes symptoms, physical functioning, work ability, social interaction, psychological functioning, treatment side effects, and financial costs. In ankylosing spondylitis, although symptoms of pain, stiffness, and fatigue are common and moderately severe, few patients develop severe functional disability and most remain employed. The limited information available suggests that most patients with ankylosing spondylitis have few problems with social interactions, although depression is not uncommon. Direct medical costs of ankylosing spondylitis are low, compared with those of other rheumatic diseases.