Mitochondrial protein import is essential for mitochondrial function, and thus the viability of most eukaryotic life, yet it has been characterized in only a few organisms. The Mitochondrial Protein Import Machinery (MPIM) database contains information on the mitochondrial protein import apparatus from a wide range of organisms, including Yeast, Human, Rat, Mouse, Drosophila, Danio rerio, Cenorhabtidis elegans, Arabidopsis, Rice and Plasmodium falciparum. Content is stored in a relational database and can be easily searched by multiple criteria. Protein and nucleic acid sequences are presented with their non-redundant NCBI accession numbers. Multiple sequence alignments between any component can be produced, as well as phylogenetic tree generation, protein motif identification, secondary structure prediction, and hydropathy plotstransmembrane region prediction.