We have studied intestinal function and liver blood flow in Thai adults with complicated and uncomplicated falciparum malaria. The absorption of 3 orally administered test sugars, D-xylose, 3-0-methyl-D-glucose, and L-rhamnose, was greatly reduced in complicated malaria, while the lactulose/rhamnose absorption ratio was significantly increased. Hepatic blood flow was concomitantly reduced in severe malaria. These deviations reverted to normal in convalescence. Neither sugar absorption nor liver blood flow was reduced in uncomplicated falciparum malaria.