Introduction: Since multidrug resistant gram negative organism have been increasing, polymyxin E(colistin) has been reintroduced despite its nephrotoxicity. Recently, Urine neutrophil gelatinase associated lipocalin(NGAL) is a promising novel biomarker that correlates with the severity and outcome of AKI. However, its performance of colistin induced AKI had not been well described. Therefore, we performed this study to estimate the diagnostic accuracy of urine NGAL for early detection of colistin induced AKI in ICU. Method: This study was prospective observational study. We enrolled the critical ill patients treated with colistin at the Chuncheon Sacred Heart Hospital. Serial urine samples were analyzed for urine NGAL. The primary outcome was AKI, defined as an RIFLE criteria. Results: Of 29 patients, 17 (58.6%) had AKI during their ICU day. Urine NGAL was significantly increased in patients with AKI (median, 140.45 ng/ml, IQR 28.92-198.7 ng/ml) compared to those without AKI (median, 47.2ng/ml, IQR 15-157.2 ng/ml, p-value=0.000). The parameter urine NGAL was a good prognostic marker for AKI development within next 72 hours (area under ROC 0.926, 95% confidential interval (CI) 0.7-0.97)). Conclusion: Urine NGAL is a useful early marker for colistin induced AKI adult ICU population, in which the timing of renal insult is largely unknown. Early identification of high risk patients may allow potentially beneficial therapies to be initiated early in the disease process before irreversible injury occurs.