A case of chloroquine-resistant Plasmodium falciparum malaria in a non-immune male is reported. Primary attack came 19 days after return to a non-malarious country from a visit to Kenya. Recrudescences occurred three times with intervals of 30 to 33 days after standard chloroquine treatment. The WHO extended field test for sensitivity of falciparum malaria to chloroquine was followed by recrudescence 31 days later. Treatment with Fansidar terminated the infection. If continuous treatment of the patient with lithium does not interfere with the schizontocidal action of chloroquine, this strain shows a resistance pattern of R I delayed recrudescence.