Mefloquine has proved effective in chloroquine- and quinine-resistant falciparum malaria, but it cannot be given parenterally. We have measured the absorption of mefloquine hydrochloride suspension (mean 15.6, range 9.7–28.6 mg/kg) given by nasogastric tube to 19 cerebral malaria patients already receiving intravenous quinine. Absorption was rapid with both dose schedules used; mean absorption half-times were 1.5 and 1.8 hr, and plasma mefloquine concentrations exceeded 200 ng/g within 3 hr of completing administration in all but one exceptionally ill patient who died 40 hr later. Steady state plasma concentrations over 7 days ranged from 300 to 1,050 (mean 561) ng/g. Bioavailability of mefloquine suspension in cerebral malaria therefore appears to be adequate for treatment in all but the most severely ill patients. Although intragastric mefloquine cannot now be recommended as an alternative to intravenous quinine for the treatment of severe chloroquine-resistant falciparum malaria, this situation could change if quinine resistance increases further.