Colistin is a re-emerging old antibiotic that is used as a salvage treatment against multidrug-resistant Gram-negative infections. Because it is administrated as an inactive prodrug, colistin methanesulfonate (CMS) that undergoes rapid hydrolyze to colistin, pharmacokinetic studies using biological assays are unreliable. With the recent development of new assays using high performance liquid chromatography (HPLC) accurate pharmacokinetic of CMS and formed colistin is now available in various populations. This article aims to update previous reports on pharmacodynamics, pharmacokinetics, safety and clinical use of colistin, with a special focus on data useful to treat critically ill patients.