Two new genes in the cytochrome P450 (CYP6) family 6 with complete coding sequences were cloned and sequenced from deltamethrin-resistant Anopheles minimus, a major malaria vector in Thailand. CYP6P5 encodes a protein of 508 amino acids, while CYP6AA2 contains 505 residues. Each encoded protein contains a hydrophobic N-terminal region and a highly conserved heme-binding region typical of P450s. Alignments of deduced amino acid sequences with other insect P450 genes indicate a high degree of identity to insect CYP6 genes. Comparative mRNA expression studies using semi-quantitative RT-PCR analysis indicated that the relative amount of CYP6AA2 transcript was greater in the deltamethrin-resistant An. minimus compared to the susceptible strain. The expression of CYP6AA2 in deltamethrin-resistant mosquitoes is associated with development of deltamethrin resistance in An. minimus mosquito. The CYP6P5 transcript is equally expressed in both resistant and susceptible mosquitoes.