Postal address:
WHO Collaborating Centre for Drug Statistics Methodology
Norwegian Institute of Public Health
P.O.Box 4404 Nydalen
0403 Oslo

Visiting/delivery address:
Marcus Thranes gate 6
0473 Oslo

Tel:  +47 21 07 81 60
Fax: +47 21 07 81 46


The basis for the ATCvet classification system is the ATC (Anatomical Therapeutic Chemical) classification system for human medicines, which was developed in Norway in the early seventies. The use of the ATC classification and the DDD (Defined Daily Dose defined as the assumed average daily dose of a substance used in its main indication in adults) as a unit of measurement was introduced in the Nordic countries in 1976.

In 1982, the WHO Regional Office for Europe established the WHO Collaborating Centre for Drug Statistics Methodology in Oslo. The main tasks of the Centre are to develop and maintain the ATC/DDD system, and to stimulate and influence the practical use of the ATC system by co-operating with researchers in the drug utilisation field.

In 1996 WHO Headquarters in Geneva decided to recommend the ATC/DDD system as an international standard for drug utilisation studies. The WHO appointed an expert group for the ATC/DDD system. The WHO International Working Group for Drug Statistics Methodology includes people from all regions. The Group meets twice annually.

The Nordic Council on Medicines established the ATCvet classification system in 1990. In January 2001, the ATCvet was taken over by the WHO Collaborating Centre. The Norwegian authorities fund the work with ATCvet.

Last updated: 2015-12-10