A life-table analysis of survival was performed retrospectively on 56 white patients (49 males) with ankylosing spondylitis. The disease was diagnosed in these patients between 1934 and 1960 at a mean age of 35.2 yr. Patients were followed until December, 1975, a mean duration of 22 yr. The expected survival was calculated from life-tables for the United States population matched for sex, age, race, geographic area, and calendar year. For the first 10 yr of follow-up, there was no difference in the observed and expected survival. By 20 yr after diagnosis, 37 patients were observed to have survived whereas 46 were expected (p = 0.001). By 40 years after diagnosis, 16 were observed to have survived and 21 were expected (p = 0.063).