The aim of this study was to investigate the clinical characteristics of patients with coexisting ankylosing spondylitis (AS) and gout. Between July 1987, and October 2004, sixty-five patients with coexisting AS and gout were enrolled. The clinical manifestations of both AS and gout in these patients were studied. Of the 65 patients included in the study, 61 were men and four were women (men-to-women ratio, 15.3:1). Sixty-three subjects were Han Chinese, and two were Atayal Aborigines. Mean ages at onset of AS and gout were 29.3 +/- 15.6 years (range 7-63) and 42.2 +/- 13.2 years (range 20-74), respectively. Fifty-six patients developed gout after (15.5 +/- 11.2 years; range, 1-51 years) onset of AS; nine patients developed gout before (average, 3.4 +/- 2.2 years; range. 1-7 years) onset of AS. Forty-four (67.7%) patients had chronic peripheral arthritis and all 65 (100%) patients had acute peripheral arthritis. Thirty-three (50.8%) cases had heel pain (enthesopathy), including 22 (33.9%) with chronic heel pain, seven (10.8%) with acute heel pain, and four (6.2%) with concurrent acute and chronic heel pain. Sixty-one (93.9%) subjects were HLA-B27 antigen positive. Medical conditions potentially associated with hyperuricemia or gout were urolithiasis (n = 17), hypertension (n = 21), diabetes mellitus (n = 8), hyperlipidemia (n = 34), congestive heart failure (n = 6), coronary heart disease (n = 5), and stroke (n = 3). The following drugs were prescribed: diuretics (n = 7), low-dose aspirin (n = 4), antituberculous drugs (n = 1), and sulphasalazine (n = 34). Six (6.2%) patients had iatrogenic Cushing syndrome with adrenal insufficiency. Patients with coexisting AS and gout are not rare. Distinguishing between peripheral arthritis or enthesopathies of AS and gout is essential, especially when the course of AS arthritis becomes acute or the course of gout becomes chronic.