An external quality assessment scheme (EQAS) for lead in blood was established in France in 1992 at the request of the Ministry of Labour and organised by the Drug Bureau. Participation is mandatory for laboratories wishing to obtain ministerial approval for the determination of blood lead levels. In 1994, two interlaboratory comparative exercises were carried out, each involving the analysis of 3 samples of human blood (2 with and 1 without lead supplementation). Out of 66 enrolled laboratories, 58 and 60 participated in the two exercises, respectively. The scattering of results was quite comparable to that observed in other EQAS. The EQAS for plasma aluminium was established in 1983 at the request of the Commission on Trace Elements of the Société Française de Biologie Clinique. Today, 80 laboratories in 22 countries on 4 continents participate in this scheme. Six exercises are carried out each year, each including 3 plasma samples (2 with and 1 without aluminium supplementation), 2 samples of water supplemented with aluminium and a blank (water). The results obtained in this scheme showed an improvement in the quality of the analyses.