The incidence of cardiovascular lesions in 97 patients with ankylosing spondylitis (AS) was found to be 14%; 8 patients had isolated aortic insufficiency (AI), 3 had isolated heart block, 2 had combined AI and heart block, and 1 had mitral insufficiency. In comparison with control groups of 81 patients with rheumatoid arthritis and 99 random hospital patients there was no increased incidence of isolated heart block in patients with AS. Clinical and postmortem findings indicated that the cardiovascular lesions of some patients with AS may antedate articular disease and may regress spontaneously. In addition, the unusual occurrence of AI in two patients with psoriatic spondylitis and in one with AS and regional enteritis is documented.