Background To compare the relative value of metabolic syndrome (MetS) and cardiovascular risk score estimates in patients with acute coronary syndromes (ACS) aged <45 years. Patients and Methods Two hundred consecutive patients (183 men, mean age 40.8 +/- 3.5 years) presented with a first-ever ACS, and 200 age-and sex-matched controls were evaluated. Metabolic syndrome diagnostic criteria, European Risk SCORE estimation function, and the Framingham Risk Score (FRS) were assessed in all participants. Results The prevalence of the MetS was significantly higher in the patients' group compared with the control group (51.5% vs 26.0%, P < .001). No subjects with a SCORE >1.0% were identified. The mean 10-year FRS for patients and controls was 13.03% +/- 7.96% and 10.02 +/- 8.10%, respectively (P < .001), whereas only 22.5% of ACS patients had a 10-year risk >20.0% compared with 14.5% of controls (P = .04). After controlling for potential confounders, MetS was associated with 1.93 (95% CI 1.13-3.28, P = .01) higher odds of having an ACS. Moreover, the odds had a positive association with the increasing cumulative number of MetS components. Crude and adjusted ORs for the FRS were 1.05 (95% CI 1.029-1.08, P = .001) and 0.98 (95% CI 0.92-1.05, P = NS), respectively. Conclusion Metabolic syndrome is highly associated with ACS in subjects <45 years of age and seems to be more valuable than established cardiovascular risk calculators.