OBJEctIVE: Colistin is a polymyxin antibiotic with a polypeptide structure and is effective against gram-negative bacilli. Although its use had decreased due to its side effects, it has increased again in recent years, especially for multi-drug resistant Pseudomonas aeruginosa, Klebsiella pneumoniae, Acinetobacter and Enterobacteriaceae. In the present study, patients that received colistin at one center were retrospectively analysed in terms of nephrotoxicity. mAtErIAl and mEtHODS: Patients hospitalized and treated with colistin in the intensive care unit between January 2012 and August 2013 were analyzed. Demographic data; biochemical tests at baseline, daily during hospitalization and after discharge; and the initial, maintenance and total doses of colistin were evaluated. rESultS: The mean age was 62±13 (31-86) years for the 27 patients with 17 (63%) males that were followed-up for an average duration of 63±89 days. During follow-up, 18 patients (66.7%) developed acute renal failure (ARF) and 17 (63%) of died. There were 12 (66.7%) mortalities in the ARF group and 5 (55%) in the group without ARF (p> 0.05). The total colistin dose and leukocyte count were higher in the ARF group with 3.75±2.34 g and 12.04±5.05/mm3 than the non-ARF group at 3.32±1.86 g and 7.60±3.7/mm3 but did not reach statistical significance. cOncluSIOn: ARF increases the mortality in ICU patients. Although colistin is an effective therapeutic agent used for resistant infections, we have to avoid higher doses due to its potential side effect of ARF.