A case of Plasmodium falciparum malaria resistant to Fansidar (sulphadoxine plus pyrimethamine) at a level corresponding to R III and resistant to chloroquine is reported. The infection was most certainly acquired in Malaysia, but diagnosed and treated in a non-malarious area. Normal resorption and elimination rates of the Fansidar components excludes cure failure due to abnormal drug fate in the host. P. falciparum parasites from the patient have been maintained in in vitro cultures. The patient was permanently cured with mefloquine.