House-spraying with fenitrothion for malaria control was evaluated in three villages of the Pout rural community (Senegal) between August 1988 and October 1990. The baseline data were collected during the first year. The malaria vector was identified as Anopheles arabiensis and the highest malaria prevalence was observed in October 1988 (38%) in the child population (2-9 years old). A simple round of fenitrothion house-spraying at 1 g/m2 was carried out in the second part of July 1989. About 90% of the houses were treated. The malaria vector was reduced to negligible density and a rapid decrease of malaria prevalence was observed. In this area of short seasonal transmission, where the stability of malaria is low, one single round of spraying led to a marked reduction of malaria transmission and prevalence. The cost of the treatment was about 50 US cents per capita.