Carbon nanotubes (CNTs) are promising drug delivery systems due to their external functionalizable surface and their hollowed cavity that can encapsulate several bioactive molecules. In this study, the chemotherapeutic drug cisplatin or an inert platinum(IV) complex were entrapped inside functionalized-multi-walled-CNTs and intravenously injected into mice to investigate the influence of CNTs on the biodistribution of Pt-based molecules. The platinum levels in vital organs suggested that functionalized-CNTs did not affect cisplatin distribution, while they significantly enhanced the accumulation of Pt(IV) sample in some tissues (e.g. in the lungs, suggesting their potential application in lung cancer therapy) and reduced both kidney and liver accumulation (thus decreasing eventual nephrotoxicity, a typical side effect of cisplatin). Concurrently, CNTs did not induce any intrinsic abnormal immune response or inflammation, as confirmed by normal cytokine levels and histological evaluations. Therefore, functionalized nanotubes represent an efficient nano-carrier to improve accumulation of Pt species in targeted tissues/organs. From the clinical editor: In this preclinical study functionalized carbon nanotubes are reported to be safe and efficient for targeted delivery of platinum-containing compounds in rodents. Approaches like this may improve the treatment of specific cancers, since platinum based chemotherapies are commonly used, yet limited by toxicity and relatively poor target tissue concentration.