Antimicrobial peptides are increasingly being explored as alternative agents for therapy against the parasitic protozoan Leishmania. Previously, we reported that the synthetic magainin analog, pexiganan, induced apoptosis of surface protease-deficient Leishmania. Here, we report the development of an arginine-rich variant of this peptide which has reduced protease susceptibility and enhanced activity against wild type Leishmania in vitro. This peptide induces calcium delocalization and caspase 3/7 activity indicative of apoptosis, demonstrating that structural modification of pexiganan leads to drastic changes in biologic activity against Leishmania.