The aim of the present study was to evaluate whether an elevated plasma C-reactive protein (CRP) level provides any additional prognostic information to the validated Thrombolysis In Myocardial Infarction (TIMI) risk score in patients with acute coronary syndromes. For this purpose, 1,846 consecutive patients with either acute ST-segment elevation myocardial infarction (STEMI; 861 patients) or non-ST-segment elevation acute coronary syndrome (NSTEACS; 985 patients) were included. The incidence of 30-day death and 14-day composite of death, myocardial infarction (or repeat myocardial infarction) and recurrent ischemia was the prespecified primary end point in the STEMI and NSTEACS cohorts, respectively. The incidence of the primary end point was 9.8% and 23.6% in the STEMI and NSTEACS cohorts, respectively. A significantly increased risk of the primary end point was present with an increase in the STEMI and NSTEACS TIMI risk score (p(trend) < 0.001 for the 2 groups). A plasma CRP value of > or = 5 and > or = 3 mg/L (defined by receiver-operating characteristic analysis) was associated with a significantly increased risk of the primary end point in the STEMI and NSTEACS cohorts, respectively (p < 0.001 for the 2 cohorts), and it was true throughout the subgroups of STEMI and NSTEACS TIMI risk scores. In conclusion, an elevated plasma CRP level appears to be a marker that adds prognostic information to the validated STEMI and NSTEACS TIMI risk score. The plasma CRP and TIMI risk score may be used together for enhanced risk stratification in the setting of acute coronary syndromes.