Objectives: The aim of this study is to compare lipoprotein (a) [Lp(a)] levels in patients with low and high risk unstable angina pectoris which is defined according to the cardiac troponin-I (Tn-I) levels and to investigate their relation with myocardial damage. Methods: From patients with chest pain; venous blood samples were collected for measuring serum Lp(a) and CRP (C-reactive protein) levels on admission and serum cTn-I levels 12 and 24 hours after admission. Fifty-nine patients with serum cTn-I levels <1.0 ng/ml were assigned as negative unstable angina group and 53 patients with serum cTn-I levels ≥1.0 ng/ml were assigned as positive unstable angi- na groups, respectively. Severity of coronary artery disease was determined by angiography in all patients. Results: Compared with cTn-I negative group, Lp(a) levels were significantly higher in cTn-I positive group (52.9±6.0 mg/dl vs 15.7±2.5 mg/dl, p<0.0001). There was a significant correlation between Lp(a) and cTn-I levels (r=0.870, p=0,0001). We could not establish any cor- relation between Lp(a) levels and Gensini score or between multiple vessel disease and LDL cholesterol levels (p>0.05). Also, there was no significant difference between cTn-I positive and negative groups with respect to Gensini score (p>0.05). Conclusion: Increased Lp(a) levels and significant relation between Lp(a) and cTn-I levels support that Lp(a) can be a risk factor for plaque destabilization and thrombosis rather than severity of coronary artery disease in patients with high risk unstable angina. Further- more, high levels of Lp(a) may be related with myocardial injury in patients with unstable angina.