Following initial evaluation children were treated with one of four drug regimens. These were SP + 1 dose of artesunate (the regimen used in the initial trial), SP + three doses of artesunate, SP + 3 doses of amodiaquine and 3 doses of amodiaquine and artesunate. Initial drug administration was given under observation. Treatment was repeated on two further occasions at monthly intervals. The health assistants responsible for giving drugs were not blinded to the study group but they played no further part in the trial. Staff who made observations in the field, for example on the prevalence of side effects, and laboratory staff were blind to the study code.