Mitochondrial (mt) DNA of the phytophagous mite Tetranychus urticae was purified and a restriction map was constructed. The 12.5 kb long genome is the shortest animal mtDNA known. A 564 bp clone comprising part of the gene for cytochrome oxidase subunit I was sequenced. As has been found in insects, the mitochondrial sequences of mites are extremely A+T rich (75% on average, 96.5% at the third codon position).