Previous reports have validated the glycogen synthase kinase-3 (GSK-3) as a druggable target against the human protozoan parasite Leishmania. This prompted us to search for new leishmanicidal scaffolds as inhibitors of this enzyme from our in-house library of human GSK-3b inhibitors, as well as from the Leishbox collection of leishmanicidal compounds developed by GlaxoSmithKline. As a result, new leishmanicidal inhibitors acting on Leishmania GSK-3 at micromolar concentrations were found. These inhibitors belong to six different chemical classes (thiadiazolidindione, halomethylketone, maleimide, benzoimidazole, N-phenylpyrimidine-2-amine and oxadiazole). In addition, the binding mode of the most active compounds into Leishmania GSK-3 was approached using computational tools. On the whole, we have uncovered new chemical scaffolds with an appealing prospective in the development and use of Leishmania GSK-3 inhibitors against this infectious protozoan. GRAPHICAL ABSTRACT ARTICLE HISTORY