Background and Objectives: Pentraxin 3(PTX3) was shown to be increasesd in the acute phase of a myocardial infarction(MI) and showed prognostic significance in MI patients. The aim of this study was to estimate whether the value of PTX3 can use as a prognostic maker in using the global registry of acute coronary events(GRACE) risk assessment tool in patients with acute coronary syndrome(ACS). Subjects and Methods: Between July 2007 and June 2008, 137 subjects(mean age: 61짹12 years, M:F=108:29) with acute coronary syndrome(ACS) underwent cononary intervention and not following coronary angiogram were enrolled. We estimated the all-cause mortality or death/MI in-hospital and for to 6 months using the GRACE risk scores and compared with serum PTX3 concentrations. Results: The serum PTX3 concentration was significantly increased in STEMI group(n=73) than in UA group(n=23)(2.4짹2.1ng/ml vs 1.3짹0.9ng/ml, p=.004) but not significantly different between NSTEMI(n=41) and UA group(2.0짹1.5 ng/ml vs 1.3짹0.9 ng/ml, p=.075, respectively). The serum PTX3 concentration was closely related to death/MI in-hospital(r=.203, p=.043) and death/MI for to 6 month(r=.204, p=.042), respectively. The serum PTX3 concentration was not related to all cause of mortality in-hospital(r=.142, p=.159) and for to 6 months(r=.153, p=.129), respectively. Among the parameters determining the GRACE risk scores, the degree of Killip class in congestive heart failure(CHF) was independently associated with the supramedian PTX3 concentration(p <.04, odds ratio: 2.23, 95% CI: 1.04–4.79). Conclusions: PTX3 is can be a useful prognostic marker in the ACS and CHF(Killip class) is an independent factor associated with for an increment of the serum PTX3 level.