A total of approximately 1205 bp long nucleotide sequences of portions of the mitochondrial 16S ribosomal DNA (16S rDNA), cytochrome b (cyt b), and cytochrome oxidase subunit I (COI) genes were determined for 7 species of the family Anthocoridae and one outgroup taxon, Nezara νiridula. Comparison of the nucleotide and inferred amino acid sequences among anthocorid taxa revealed the biased nature of nucleotide substitutions in the 2 protein-coding genes. In the 16S rDNA, although strong A+T composition bias and A-T transversion bias were evident among anthocorid taxa, uncorrected genetic divergence increased linearly with the increase of the taxonomic levels. Results of preliminary phylogenetic analyses revealed that the nucleotide sequences of the 2 protein-coding genes are useful for the estimation of the relationship among taxa at lower taxonomic levels compared with the 16S rDNA.