The WHO international external quality assessment scheme for haematology.

Quality assurance is essential in laboratory medicine; an important component is external quality assessment in order to ensure that reliable performance is achieved by all laboratories and that between-laboratory comparability is maintained. In a number of countries there are national external quality assessment schemes. WHO has established a programme aimed at encouraging the organization of similar schemes in all countries. Towards this goal an international external quality assessment scheme has been established for each of the specialities of haematology, clinical chemistry, microbiology and parasitology.This paper describes the organization of the international scheme for haematology. There are now 62 laboratories taking part in 49 countries. The functioning of the scheme, the participants' response, and the extent to which the scheme has improved the standard of practice in their laboratories are described.