A randomised controlled trial was carried out to determine the relative efficacy of four commonly used antimalarial drugs in children aged three to twelve years presenting with uncomplicated malaria at the Eldoret District Hospital, Kenya. One hundred and eighty eight children were studied between July 1993 and July 1994. There were no significant baseline differences between treatment groups with respect to age, sex, weight, ethnicity, haemoglobin, white blood cell (WBC) counts, parasite counts, previous exposure to malaria and prior treatment. Of the 188 patients, eleven were lost to follow-up while twelve were discontinued from the study due to poor clinical response. Most of the latter (eight out of twelve) were in the chloroquine group. By day seven, there were significant differences (p = 0.004) in parasite clearance between groups. There were no significant statistical differences between the groups (p = 0.12) with regard to the fever clearance time. However, there was a significant statistical difference (p = 0.00003) between the treatment groups in the cure rates. Halofantrine was the most efficacious drug with 82% of the cases cured followed by fansidar(R)(62%), amodiaquine (55%) and chloroquine (29%). RI and RII resistance were observed in all the treatment groups, i.e. halofantrine (18%), fansidar (38%), amodiaquine (45%) and chloroquine (67%) while RIII resistance was only observed in the chloroquine group(3%).