Resistance to the antifungal drug Amphotericin B (AmB) has not evolved but it is extremely toxic to humans. AmB extracts the fungal sterol ergosterol from fungal membranes and its toxicity probably results from cross-reactivity with human cholesterol. Davis et al. designed a new class of non-toxic amphotericins that are readily synthesized from AmB. Crucially, the disruption of a salt bridge in AmB produces an alternative conformer that binds to ergosterol but not cholesterol. In vitro tests showed potency against several fungal pathogens but little or no human toxicity. In a mouse model of candidiasis, one compound, AmBMU, was more potent than AmB, with no observed toxicity. A small number of mutations were identified that conferred resistance to AmBMU but these rendered the pathogen avirulent, suggesting that the use of non-toxic amphotericins is unlikely to select for drug resistance.