The International Code of Nomenclature of Prokaryotes (ICNP) formerly the International Code of Nomenclature of Bacteria (ICNB) or Bacteriological Code (BC) governs the scientific names for Bacteria and Archaea. It denotes the rules for naming taxa of bacteria, according to their relative rank. As such it is one of the nomenclature codes of biology.
Originally the International Code of Botanical Nomenclature dealt with bacteria, and this kept references to bacteria until these were eliminated at the 1975 International Botanical Congress. An early Code for the nomenclature of bacteria was approved at the 4th International Congress for Microbiology in 1947, but was later discarded.
The latest version to be printed in book form is the 1990 Revision, but the book does not represent the current rules. The 2008 Revision has been published in the International Journal of Systematic and Evolutionary Microbiology (IJSEM). Rules are maintained by the International Committee on Systematics of Prokaryotes (ICSP; formerly the International Committee on Systematic Bacteriology, ICSB).
The baseline for bacterial names is the Approved Lists with a starting point of 1980. New bacterial names are reviewed by the ICSP as being in conformity with the Rules of Nomenclature and published in the IJSEM.
As of 2011, the formal separation of the botanical and bacteriological codes continues to cause problems with the nomenclature of certain groups.