Do we need to accredit proficiency testing schemes?

Proficiency testing (PT) is being increasingly used as an important quality assurance tool for laboratories. The subject of quality of the providers o f PT schemes has been discussed increasingly in recent years. Some countrie s have implemented systems for the accreditation of PT schemes. This paper looks at the background to the accreditation of PT schemes, the likely mech anisms which could be employed for accreditation, and some of the practical aspects.