We investigated survival of a group of 151 Canadian war veterans with ankylosing spondylitis who were entered into a prospective study in 1947-1949. With 94% successful followup, total survival was 60.9%, significantly less than expected. However, a subgroup who had not been treated with radiotherapy had a survival not significantly different from the general population. Causes of death in both irradiated and nonirradiated subgroups were determined.