Pyrethroid resistance is a serious threat to the continued usefulness of insecticide-treated nets to control malaria vectors. It is therefore important to investigate alternative insecticides. Encouraging results have been achieved with the carbamate carbosulfan in C?te d'Ivoire where Anopheles gambiae has high frequency of the kdr pyrethroid resistance gene (KOLACZINSKI, J. et al., 2000: Bulletin of Entomological Research, 90, 125-132). The present laboratory investigation was on the insecticidal and irritant effect of carbosulfan on pyrethroid-resistant strains of An. gambiae originating from Burkina Faso (West Africa) and An. stephensi from Dubai and on susceptible strains of each species. The mosquitoes were exposed to nets with doses of carbosulfan ranging from 12.5 to 400 mg/m? and were re-tested at 3 and 6 months. There was little variation with dose or age of net in mortality or irritancy, as measured by time for first take-off. However, both pyrethroid- resistant strains showed reduced irritancy compared to the susceptible strains in response to carbosulfan. Both pyrethroid-resistant strains, especially the Dubai strain, showed partial cross-resistance, in terms of mortality, on carbosulfan.