The recommended dose of 10 mg quinine/kg bodyweight 3 times a day for 7 days for treatment of malaria is so high that many patients experience cinchonism. We have earlier obtained good results with 7 days' treatment with 20 mg Quinimax/kg bodyweight divided into 2 daily doses. In order to identify the lowest effective dose, children with symptomatic malaria were treated with quinine twice a day for 7 days. They were assigned to 1 of 3 groups treated daily with 10 mg/kg, 15 mg/kg, or 20 mg/kg bodyweight, respectively; 42, 46, and 34 children, respectively, received treatment and completed 5 weeks of follow-up. The cumulative percentages of all children with parasitaemia during follow-up on day 28 or before were 33%, 13% and 12%, respectively. Treatment with 10 mg quinine salt/kg daily for 7 days gave a significantly higher rate of recrudescence than did treatment with 15 or 20 mg/kg daily. Thus at least 15 mg of quinine salt/kg bodyweight daily should be recommended for treatment of symptomatic Plasmodium falciparum malaria in Guinea-Bissau.