We conducted the present study to determine whether subclinical macrovascular atherosclerotic disease was present in patients with ankylosing spondylitis (AS) without clinical history of cardiovascular disease. We also sought to establish whether demographic or clinical features of the disease may influence the development of subclinical atherosclerotic disease in a series of patients with AS seen at a community hospital. We recruited 64 patients who fulfilled the modified New York diagnostic criteria for AS from Hospital Xeral-Calde, Lugo, Spain. We excluded patients seen during the recruitment period who had cardiovascular disease or renal insufficiency. We also studied 64 matched controls. Carotid artery intima-media thickness (IMT) and carotid plaques were measured in the right common carotid artery. The study was performed using high-resolution B-mode ultrasound.Patients with AS exhibited greater carotid IMT than did matched controls (mean +/- SD, 0.74 +/- 0.21 mm vs. 0.67 +/- 0.14 mm; p = 0.01; differences of means, 0.077; 95% confidence interval, 0.016-0.139). Carotid plaques were more commonly observed in patients with AS than in controls (19 [29.7%] vs. 6 [9.4%], respectively; p = 0.03). The best predictors for carotid plaques in patients with AS were erythrocyte sedimentation rate (ESR) at time of disease diagnosis (odds ratio [OR], 1.18; 95% confidence intervals [CI], 1.04-1.33; p = 0.01) and duration of disease (OR, 1.39; 95% CI, 1.01-1.92; p = 0.05). In contrast, there was no significant correlation between carotid IMT and either ESR or C-reactive protein in this study. Results of the present study show that patients with AS without clinically evident cardiovascular disease have a high prevalence of subclinical macrovascular disease in the form of increased carotid IMT and carotid plaques compared to matched controls.