Since August 1983, several cases of chloroquine resistant malaria have been observed in caucasian adults living in the Central African Republic (CAR) despite an antimalarial prophylaxis. Between 1984 and 1985, several studies including both in vitro and in vivo tests have been undertaken in cohorts of children to determine antimalaria drug sensitivity of P. falciparum in two towns of the CAR. In Bangui, out of 60 asymptomatic schoolchildren with asexual parasite count per mm3 of blood equal (or more than) 1,000, treated using a single intake of chloroquine at a dose of 10 mg/kg, three had asexual parasites at day 7 after drug administration. Alternatively, out of 57 other children with clinical malaria treated using a total dose of 25 mg/kg of chloroquine daily distributed within a 3 day period, only one exhibited a RII resistance. In vitro tests performed in a limited cohort of 15 school children showed a high sensitivity to chloroquine, amodiaquine, quinine and mefloquine in P. falciparum malaria. In Bouar, a group of 80 preschool children attending pediatric clinic were treated using either a single dose of 10 mg/kg of chloroquine (25 children) or 25 mg/kg of amodiaquine (21 cases) or 25 mg/kg of chloroquine (34 cases) within a three days period. Asymptomatic parasitaemia persisted or reappeared in 6 children all treated with 10 mg/kg of chloroquine. Therapeutic response to amino-4-quinolines in central african children is up to now satisfactory as compared to that observed in surrounding countries. Further surveys including other rural and urban areas are needed to appreciate the evolution of the phenomenon.