The fiber-type nomenclature of human skeletal muscle preferred by the author is “type I” and “type II” fibers, based on their light or dark staining respectively with the myofibrillar adenosine triphosphatase reaction (pH 9.4) of Padykula and Herman. All other terms and histochemical reactions have greater disadvantages than this nomenclature. Needs for the future include (1) establishing a consistent histochemical subtyping system for human skeletal muscle fibers, (2) directly correlating in human fibers the basic histochemical types and subtypes with physiologic, biochemical and other parameters, and (3) further identifying histochemical changes that preferentially affect one fiber type or subtype in various human diseases and altered physiologic states.