The toxicity of methylated coconut oil (MCO) was compared with a commercially available oil larvicide (Golden Bear Oil ® GB-1111) in laboratory bioassays of 4th-stage larvae of Anopheles farauti Laveran and Culex annulirostris Skuse. Both larvicides were more toxic to Cx. annulirostris than to An. farauti and the LD₅₀ (dose lethal to 50% of the test organisms) after 24 h exposure indicated that MCO was more toxic than GB-1111 for both An. farauti (LD₅₀ = 8.6 μl versus 13.0 μl/156 cm2) and Cx. annulirostris (LD₅₀ = 1.2 μl versus 3.6 μl/156 cm2). However, for LD₉₅ GB-1111 was more toxic than MCO for both An. farauti (LD₉₅ = 29 μl versus 48.0 μl/156 cm2) and Cx. annulirostris (LD₉₅ = 7.2 μl versus 18.0 μl/156 cm2). Further study of MCO is warranted and may determine whether the addition of surfactant to MCO will lower the LD_95. The possibility of community participation in the production and use of coconut products including MCO for malaria vector control is discussed.