BACKGROUNDS AND OBJECTIVES: C-Reactive protein (CRP) levels are powerful predictors of cardiac complications and death in patients with unstable angina unrelated with myocardial cell damage or myocardial ischemia. This study was performed to determine the optimal timing to measure CRP to predict cardiac events in patients with unstable angina. MATERIALS AND METHOD: The study was comprised 50 patients with unstable angina (Braunwald Class IIIb). We randomized the study subjects by the time of CRP elevation (> 8mg/L): Group A (on admission, 15 patients), Group B (during hospitalization, 19 patients), and Group C (at discharge, 19 patients). RESULTS: 1) CRP levels (median and range) of Group A, B, and C were 10.6 (8.2-24.2), 12.8 (8.1-33.7), and 10.3 (8.1-18.7) mg/L, respectively (p=S). 2) During clinical follow-up at a mean duration of 12 months, there were 1 death, 1 myocardial infarction, 6 revascularization therapy (PTCA or CABG) and 11 recurrent angina. 3) In Group A, 10 cardiac events (1 myocardial infarction, 4 revascularization therapy, and 5 recurrent angina) occurred. The elevated levels of CRP predicted cardiac events during clinical follow-up with sensitivity of 53%(10/19), positive predictive value of 67%(10/15), and negative predictive value of 74%(26/35). In Group C, 13 cardiac events were occurred. Sensitivity, positive and negative predictive value to predict cardiac events of elevated levels of CRP were 68%(13/19), 68%(13/19) and 81%(25/31), respectively. 4) Elevated levels of CRP (>8mg/L) were predictors for cardiac events in patients with unstable angina (Group A; p<0.05, Group B; p<0.05, Group C; p<0.001). However, by logistic regression analysis, CRP values > 8mg/L at discharge were only predictive of cardiac events with odd ratio of 6.01 (95% CI 1.50-44.3, p<0.05). CONCLUSIONS: CRP (> 8mg/L) was elevated in 38% of patients at discharge and elevated levels of CRP at discharge were only predictive of cardiac events in patients with unstable angina.