The effect of single oral doses of albendazole 600 mg and mebendazole 1 g given to 56 and 60 men, respectively, with T. trichiura and/or N. americanus infestation has been studied. Both albendazole and mebendazole cured more than 90% of T. trichiura infestations, but only albendazole (95%) and not mebendazole (21%) had a high cure rate for N. americanus infestations. Thus, albendazole is the preferred benzimidazole derivate for the mass treatment of subjects with T. trichiura and/or N. americanus infestations.