Animal mitochondrial DNA as a genetic marker has been used extensively in many biological fields from intraspecific to higher taxonomic categories.Most of these applications are based on the properties of strict maternal inheritance and non-recombination of mtDNA.Recent studies have provided some indirect and direct evidence of animal mtDNA recombination.Animal mtDNA recombination might occur by two main pathways,recombination between the maternal mtDNA and a nuclear encoded pseudogene copy of mtDNA and the combination between paternal and maternal mtDNA haplotypes through paternal leakage.Paternal leakage appears to be the most plausible pathway of mtDNA recombination.If animal mtDNA recombination occurs commonly in animal kindom,it will have significant influences to many application areas based on strict maternal inheritance.