Deet and permethrin were evaluated as protectants against Plasmodium falciparum-infected, P. berghei-infected and uninfected Anopheles stephensi mosquitoes. Deet 50% effective dose (ED50) values were 3.2 micrograms/cm2 for P. falciparum-infected and 1.9 micrograms/cm2 for uninfected mosquitoes; permethrin values were 0.5 micrograms/cm2 and 0.6 micrograms/cm2, respectively. Deet ED50 values were 2.3 micrograms/cm2 for P. berghei-infected and 1.3 micrograms/cm2 for uninfected mosquitoes; the permethrin values were both 0.5 micrograms/cm2. There were no significant differences in the protective efficacy of deet or permethrin between malaria-infected and uninfected An. stephensi mosquitoes.