To evaluate the prevalence of the metabolic syndrome in patients with rheumatoid arthritis (RA), ankylosing spondylitis (AS), and psoriatic arthritis (PsA). Consecutive patients with RA, AS, or PsA who attended our outpatient arthritis clinics between July and November 2009 were recruited for a study of atherosclerotic risk factors and the metabolic syndrome, defined according to the 2009 joint statements using the Asian criteria for central obesity. Nine hundred thirty patients were studied (699 with RA, 122 with AS, and 109 with PsA; 70% women, mean±SD age 51.1±12.7 years). The mean±SD disease duration for patients with RA, AS, and PsA was 5.3±5.4, 6.0±5.6, and 3.6±3.1 years, respectively. The prevalence of metabolic syndrome was significantly higher in PsA (38%) than RA (20%) or AS (11%; P<0.001). The odds ratios (ORs) for the metabolic syndrome compared to age- and sex-matched controls were 0.98 (95% confidence interval [95% CI] 0.78-1.23, P=0.88), 0.59 (95% CI 0.30-1.15, P=0.12), and 2.68 (95% CI 1.60-4.50, P<0.001), respectively, for RA, AS, and PsA. Patients with PsA had a significantly higher prevalence of impaired fasting glucose (30%; P<0.001), low high-density lipoprotein (HDL) cholesterol (33%; P<0.001), high triglycerides level (21%; P=0.008), central obesity (65%; P<0.001), and high blood pressure (56%; P=0.045). In a logistic regression model, the adjusted OR for the metabolic syndrome in PsA was 2.44 (95% CI 1.48-4.01, P<0.001) relative to RA or AS. The adjusted ORs for central obesity, impaired fasting glucose, hypertriglyceridemia, and low HDL cholesterol were also significantly higher in PsA patients. Patients with PsA, but not RA or AS, have a significantly higher prevalence of the metabolic syndrome compared to the general population. Among the 3 diseases studied, PsA has the highest prevalence of the metabolic syndrome and is associated with the highest cardiovascular risk. Copyright © 2011 by the American College of Rheumatology.