Hypoglycaemia, defined as a plasma glucose concentration below 2.2 mmol/l, developed in 15 of 47 prospectively studied Gambian children with severe chloroquine-sensitive falciparum malaria. 5 of these hypoglycaemic children died compared with 1 in the normoglycaemic group (p = 0.02). In contrast to previous observations in quinine-treated adults, in whom hypoglycaemia was associated with hyperinsulinaemia, plasma concentrations of insulin were appropriately low and plasma ketones were high. Raised plasma concentrations of lactate and alanine suggested impairment of hepatic gluconeogenesis. In African children, hypoglycaemia is an important and treatable manifestation of severe malaria and is unrelated to antimalarial treatment.