A web-based database of human whole genome and complete coding region sequences. mtDB is the only comprehensive online source for the data contained within it. This includes the sequences themselves as many have not been deposited in a publicly available database such as GenBank. The list of mitochondrial polymorphisms continually grows with the addition of new sequences and is an important resource for phylogenetic and medical studies. The ability to search for multiple-variant haplotypes adds further detail to the latent data.