Two immunodeficient children, aged 4 and 12 years, with crusted scabies were successfully treated with a single oral dose of ivermectin (200 micrograms/kg). One child had been diagnosed in infancy with an undefined congenital T cell immunodeficiency and the other with chronic mucocutaneous candidiasis. Both had failed to respond to conventional topical therapy. In view of the excellent therapeutic response and absence of side-effects, ivermectin should be considered in the treatment of recalcitrant crusted scabies in children.