The entire 15,363 bp mitochondrial genome was cloned and sequenced from the mosquito Anopheles gambiae. With respect to the protein-coding genes, rRN A genes and the control region, the gene order was identical to that reported for other insects. There were significant differences, however, in the position and orientation of specific tRNA loci. The overall nucleotide composition was heavily biased towards adenine and thymine, which accounted for 77.6% of all nucleotides. Comparisons were made with the mitochondrial genomes of other insects on the basis genome size and organization, DNA and putative amino acid sequence data, nucleotide substitutions, codon usage and bias, and patterns of AT enrichment.