There is a growing awareness of the role of cardiac troponin-I (cTnl) in detecting patients with unstable angina (UA) who are at high-risk of subsequent cardiac events, for whom prompt intervention is highly indicated. Objective: To evaluate role of cTnl in detecting this high-risk subgroup of UApatients. Patients andMethods: Quantitative serumcTnl level was measured in 100 patients withUA, 12h, 24h and 48h after admission to the hospital; serum CK &CK-MB activity was also measured at the same time intervals to exclude acuteML The studied population was classified into two groups; group I included 55 patientswho showed normal cTnl level (< 0.6ng/ml) and group II included 45 patients who had such abnormal level (> 0.6ng/ml). Resting 12 lead-ECGswas done on admission, twice daily, and whenever needed. All patients underwent coronary and LV angiographic studies before hospital discharge andwere clinically followedup for threemonths to detect any of the following adverse events: death, progression of UA toMI or need for emergency PTCA / CABG. Results: Compared to group I, group II patients had statistically significant highermean age (P< 0.05), higher prevalence of diabetes (P < 0.05), higher incidence of Braunwald class III UA (P< 0.01), and higher incidence of marked ST-T changes (P < 0.001). Male sex, hypertension or hypercholesterolemiawas not statistically different between both groups.Quantitative angiographic data revealed a higher mean of percentage diameter stenosis (P 0.05) in group II compared to group I. Nearly all those who had subsequent adverse cardiac events showed a positive test for serum cTnl. Conclusion: An abnormal cTnl serum level is commonly associated with severe UA,more extensive and complex coronary artery disease, high-risk angiographic anatomy of the culprit lesion and a poor clinical outcome in patients with UA. Serum cTnl is a simple and non-invasive test,which can be used to stratify patients with unstable angina into low- and high-risk groups very early (within 48h) in the course of the disease; so it is useful in targeting the new, potent and often costly lines ofmanagement such as revascularization procedures and the newer antithrombotic andantiplatelet agents for the high-risk UA population.