On August 19, 1967, an informal meeting organized by T. Kimura was held in Tokyo, Japan, to discuss the needs and desires of establishing a systematic nomenclature for the so-called "non-heine iron proteins". The eighteen scientists attending that meeting--all actively investigating the chemistry or biological function of this unique class of proteins-agreed that the time ~was propitious to stetil the proliferation of trivial naines that had developed in the last few years, and that the IUPAC-IU~B Commission on Biochemical Nomenclature (CBN) be requested to form a subcommittee to establish tentative rules for nomenclature. This recommendation was accepted by CBN at their meeting inBellagio, Italy, in July !968 and a sub~ommission was establishedL A formal meeting of the subcommission was held on October 17, 1968, and a provisional system of nomenclature was discussed. Of primary importance was the unanimous agreement that the term "nonheine iron proteins" be abandoned. I t was proposed that the general category of iron-containing proteins should have a subdivision composed of "iron-sulfur proteins". Further it was agreed that the terms "ferredoxin" and 'rubredoxin" be retained and their usage expanded.