A clinical and radiographic study of 98 patients with definite ankylosing spondylitis (Rome criteria) was undertaken to evaluate differences in men and women with the disease. Clinical manifestations which were atypical in the 18 female patients when compared to those of the men included older age of disease onset, higher incidence of initial and subsequent peripheral joint disease, more common cervical spine symptomatology, and milder disease course. Radiographic differences in the women included a high incidence of cervical spine abnormalities, a combination of cervical spine and sacroiliac joint alterations with a normal intervening thoracic and lumbar segment, and frequent and severe osteitis pubis.