A leaf-extract of Ocimum basilicum (sweet basil) was used in formulating an aerosol and mosquito coil, and their efficacy rested against adult mosquitoes. The formulations had potencies of 93 +/- 4 and 95 +/- 5% for the aerosol and coil, respectively. The efficacy of the formulations depended on the duration of fumigation. The formulations also included the synergist, piperonyl butoxide. The plant can, therefore, serve as a substitute for some expensive synthetic insecticides which have toxic residual effects.