Polymyxin B (PB) is a polypeptide bactericidal antibiotic that is commonly used for extensively drug-resistant (XDR) microorganisms such as Acinetobacter baumanii and Klebsiella pneumoniae It can be administered intravenously or intrathecally. Common side effects are nephrotoxicity, neurotoxicity, pruritus and skin hyperpigmentation (SH). The latter is an uncommon adverse reaction of intravenously administered PB. We report a rare occurrence of PB-induced SH secondary to intrathecal administration of PB in a child with A. baumanii XDR ventriculitis. We describe the management of him and a brief review of PB.