Plant mitochondria maintain metabolic communication with the cytosol through a family of carrier proteins that share several structural features. Early studies led to the recognition of several mitochondrial transport activities but the proteins responsible for these activities had not been identified. The in silico analysis of the complete Arabidopsis genome has revealed almost 60 genes encoding putative members of the mitochondrial carrier family. Recombinant protein technology and functional reconstitution techniques developed for animal and yeast carrier proteins are currently being combined with a wide range of functional-genomics tools to identify and characterize mitochondrial carriers in plants. This information is crucial for obtaining an integrated view of mitochondrial function in plant cell metabolism.