We conducted the current study to search for subclinical atherosclerosis in patients with rheumatoid arthritis (RA) without clinically evident atherosclerosis or its complications who had been treated for a long duration, and to assess whether demographic or clinical factors affect the development of atherosclerotic disease. Forty-seven white patients fulfilling the 1987 American College of Rheumatology classification criteria for RA were recruited from Hospital Xeral-Calde, Lugo, Spain. Patients were required to have been treated for at least 5 years, including current treatment with 1 or more disease-modifying antirheumatic drugs. Patients with diabetes mellitus, renal insufficiency, hypertension, cardiovascular or cerebrovascular disease, and smokers were excluded. Forty-seven matched controls were also studied. Carotid intima-media wall thickness (IMT) and carotid plaques were measured in the right common carotid artery. The study was performed using high-resolution B-mode ultrasound. Patients had greater carotid IMT (0.779 +/- 0.164 mm) than did controls (0.699 +/- 0.129 mm); (p = 0.010). Sixteen (34%) patients showed carotid plaques compared with only 7 (15%) controls (p = 0.031). There was a positive correlation between the age at the time of study and the carotid IMT. Patients with carotid plaques had significantly greater carotid IMT (0.859 +/- 0.116 mm) than those without plaques (0.739 +/- 0.171 mm) (p = 0.014). Also, RA patients with carotid plaques had a significantly longer disease duration (mean, 21.0 yr) and more extraarticular manifestations (63%) than those without plaques (mean, 12.7 yr and 26%, respectively). Age at the time of the study and disease duration were the best predictive factors for the development of severe morphologic expression of atherosclerotic disease. The present study confirms an increased frequency of severe subclinical atherosclerotic findings in long-term actively treated RA patients from northwest Spain.