AIM To describe the scientific contributions and biography of Giuseppe Attardi (1923-2008), in particular his work on the human mitochondrial genetic system of crucial importance for the discovery and understanding of the mechanisms that produce the mitochondrial diseases. DEVELOPMENT. Giuseppe Attardi was an Italian-born medical doctor that worked with outstanding researchers as James Watson, François Jacob, and Renato Dulbecco, all Nobel Prizes of Medicine until 1963 that was promoted to Professor of the California Institute of Technology in Pasadena (USA). In 1967 discovered the human mitochondrial RNA, a little later the mitochondrial ribosomes and proteins encoded in the genome, in 1981 showed the genetic and transcription map of the mitochondrial DNA, and in 1983 described the proteins codified in this genome, all of them components of the oxidative phosphorylation system, metabolic pathway that leads to the synthesis of ATP. Later, he developed a technique, widely used nowadays, to study the mechanism by which the mutations in the mitochondrial DNA altered the cellular function and originated the mitochondrial diseases. In 1999, demonstrated the role of the mitocondrial DNA, and the mutations produced along the life, in aging.