Patients with ankylosing spondylitis (AS) have about a 50% increased risk of mortality on the basis of the limited amount of data available. There is some evidence that the progression of disease is strongest in the first 10 years of disease but it is also clear that the disease keeps on being active for further decades. The overall burden of disease is similar to rheumatoid arthritis but the overall disease duration of AS is longer. Prognostic factors have also not been studied extensively in AS but it seems clear that early hip involvement indicates a worse outcome. The same is true for early limitation of spinal mobility, laboratory evidence of ongoing disease activity (ESR, hypergammaglobulinemia), peripheral arthritis and dactylitis. The significance of organ involvement for the prognosis, especially in the kidney in the form of amyloidosis, and in the heart and lungs, is less clear. Radiation therapy of the spine, which had been performed quite extensively in former decades, has been associated with a mean radiation dose of about double that of atomic bomb survivors and an increased risk of leukemia and mortality. This therapy has been largely abandoned nowadays. Elder rheumatologists report however that the clinical improvement of irradiated patients has been partly impressive.