AbstractAgainst Cryptosporidium parvum only nitazoxanide and paramomycin show some activity in immunocompromised patients such as those with AIDS. In immunocompetent children and adults, nitazoxanide receives regulatory approval for this indication in the USA. New targets include the epidermal growth factor (EGF) receptor, pp60v-src and pp110gag-fes, and new isoflavone derivatives have shown in vitro and in vivo activities against C. parvum. The nitroimidazoles such as metronidazole and tinidazole are effective treatments against giardiasis and could be given in a single dose. Albendazole and nitazoxanide are two effective antigiardial drugs but require multiple doses. Compounds active against protein disulphide isomerases, more specifically PDI2 and PDI4, as recently reported, could also represent promising targets for new drugs effective against Cryptosporidium spp. and Giardia intestinalis, respectively. There is little doubt that more antiprotozoal drugs are needed.