>Background: Percutaneous coronary intervention (PCI) is a most effective treatment of acute coronary syndrome to restore the blood flow within the culprit artery. But there are many patients who can not undergo PCI because of poor general condition or hospitals without on-site invasive facility. Therefore, proper conservative treatment is very important in this situations. The aim of this study was to assess the impact of more aggressive pharmacological treatment with a special focus on its influence on in-hospital mortality in NSTEMI patients. Methods: 981 NSTEMI patients treated with early conservative strategy (mean age = 67.8짹13.1 years, 576 males) in the 40 hospitals, which were high-volume centers with facilities for PCI and on-site cardiac surgery, was included in KAMIR from Nov 2005 to Dec 2006. For all patients, pharmacotherapy index based on the use of drugs during hospital stay and discharged period was assessed. Each patient received 1 point for each of the following guideline-recommended drugs used: aspirin, clopidogrel, glycoprotein IIb/IIIa inhibitor, low-molecular-weight/unfractionated heparin, beta-blocker, angiotensin converting enzyme inhibitor/angiotensin II receptor blocker, statin - range of points from 0 to 7. Primary end points is in-hospital mortality, morbidity, and major adverse cardiac event (MACE) during 6 months follow-up. Results: The in-hospital outcome and MACE for 6 months decreased with increase of pharmacotherapy index [0 points (n=19): 42.1 %, 1 point (n=15): 40.0 %, 2 points (n=44): 27.3 %, 3 points (n=107): 26.2 %, 4 points(n=157): 22.3 %, 5 points (n=271): 20.3 %, 6 points (n=340): 19.4%, 7 points (n=28): 14.3 %; P=0.001, total primary endpoints: 21.8 %. Independent predictors of primary end points were killip class, pharmacotherapy index, NT-proBNP (OR=1.95, 0.80, 1.43, p<0.001, 0.022, 0.023, respectively). Conclusions: More intensive pharmacological treatment may improve clinical outcome in patients with NSETMI with early conservative treatment. Our findings support the need for more intensive pharmacological treatment of patients with NSTEMI.