The efficacy of quinine prescribed to children from Brazzaville hospitalized for acute malaria (temperature over 38 degrees C, P. falciparum parasitaemia over 10,000/mm3, no other obvious disease; the reason for hospitalisation often being digestive or neurological disorders) was assessed. Quinine was administered by perfusion: 25 mg/kg/day for at least 3 days. Associated treatment (sulfadoxine-pyrimethamine combination in 80% of the cases) was given at day 3. Blood was taken at day 0, and before discharge (usually between days 3 and 5). Thick Blood Smears (TBS) were examined for a volume of blood corresponding to 300 leucocytes. Antimalarials had been taken in 60% of the cases (chloroquine in 67% of the cases, quinine in 10%). Antimalarials were not assayed in the sera. In 68 cases of non pernicious malaria, no obvious cases of resistance were observed. TBF were negative in 49 out of 52 cases at day 3, and 11 out of 12 at day 4 and in five out of five cases at day 5. In 96 cases of pernicious malaria, only one case was suspected of being resistant, with a weakly positive TBS at day 7. 13 children died but all in the first three days without suspicion of resistance. Apyrexia was observed before day 4 in 89% of the cases; only one case of fever at day 7. TBS were negative before day 4 in 97% of the cases. So, at the dosage of 25 mg/kg, quinine was found to be very effective in the Congo in 1989 against both pernicious and non pernicious malaria.