Abstract Leishmaniasis is a neglected disease threatening over 350 million people. Antimonials are first‐line drugs due to resistance and side effects there is a demand for alternative chemotherapy. Itraconazole (ITZ) is an antimycotic. It was encapsulated into poly(lactic‐ co ‐glycolic acid) (PLGA) nanoparticles (NPs) and covered with mannose. The NPs were 250 nm and −1.1 mV ± 0.7. PLGA‐ITZ‐mannose NPs presented a toxicity of 20.7% for J774 cells, and no toxicity for THP 1. The J774 cells were infected with three Leishmania promastigotes strains and treated with ITZ loaded PLGA NPs with/without mannose. The parasite percentage of L.(V.) panamensis intracellular amastigotes significantly ( p < 0.01) decreased from 34.4% to 13.7% and 5.7% for PLGA‐ITZ‐mannose NPs and PLGA‐ITZ NPs, respectively. For L.(L.) infantum there was a reduction ( p < 0.001) from 18.1% to 4.8% and 8.3% for PLGA‐ITZ‐mannose NPs and PLGA‐ITZ NPs, respectively. Further with L.(L.) braziliensis amastigotes there was a significant reduction ( p < 0.001) from 54.9% to 28% and 21.1% for PLGA‐ITZ‐mannose NPs and PLGA‐ITZ NPs, respectively. Adding mannose increased the efficacy PLGA‐ITZ NPs against L.(L.) infantum , while it had no effect against L(V.) panamensis and L.(L.) braziliensis amastigotes. We recommend further investigation of PLGA‐ITZ‐mannose NPs in animal models to evaluate their potential. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 00B: 000–000, 2018. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 680–687, 2019.