Definitive Rules for Nomenclature of SteroidsThese Rules shall be known as the IUPAC-IUB 1971 Definitive Rules for Steroid Nomenclature.These Rules are issued by the IUPAC Commission on the Nomenclature of Organic Chemistry and by the IUPAC-IUB Commission on Biochemical Nomenclature.Those who have served on the Commission on the Nomenclature of Organic Chemistry for varying periods during 1967–71 are the following. Present members are shown by an asterisk*. P. E. Verkade (Chairman to 1971), N. Lozac’H* (Chairman from 1971), K. Bláha*, L. C. Cross*, G. M. Dyson, S. P. Klesney*, W. Klyne*, K. L. Loening*, H. S. Nutting, J. Rigaudy*, S. Veibel*. Associate members: R. S. Cahn, H. Grünewald*, K. Hirayama*. Observer: K. A. Jensen*.Those who have served on the Commission on Biochemical Nomenclature for varying periods during 1967–71 are the following. Present members are shown by an asterisk*. O. Hoffmann-Ostenhof* (Chairman), A. E. Braunstein*, W. E. Cohn* J. S. Fruton, B. Horecker*, P. Karlson*, B. Keil*, W. Klyne*, C. Liébecq* E. C. Slater, E. C. Webb*, W. J. Whelan*. Observer: S. Veibel*.Comments on and suggestions for future revisions of these Rules should be sent to: Professor N. Lozac’H. Ecole nationale supérieure de Chimie, 5 Avenue d’Edimbourg, F-14 Caen, France, or Professor O. Hoffmann-Ostenhof, Lehrkanzel für Biochemie der Universität Wien, Währingerstrasse 38, 1090 Vienna, Austria, or to any present member of the Commissions named above.