The AMmtDB database (http://bio-www.ba.cnr.it:8000/srs6/ ) has been updated by collecting the multi-aligned sequences of Chordata mitochondrial genes coding for proteins and tRNAs. The genes coding for proteins are multi-aligned based on the translated sequences and both the nucleotide and amino acid multi-alignments are provided. AMmtDB data selected through SRS can be viewed and managed using GeneDoc or other programs for the management of multi-aligned data depending on the user's operative system. The multiple alignments have been produced with CLUSTALW and PILEUP programs and then carefully optimized manually.