In the Hospital Services of Occupational health stated in Lombardy Region from seventies, among the other sections laboratories of Industrial Hygiene and Toxicology have been organized. These laboratories performed the routinary analyses and some of them deepened specific toxicological aspects (metals in Brescia, solvents in Pavia, neurotoxicants in Milan). During 1996 about 50,000 analytical determinations and several investigations and researches have been carried out. The laboratories, moreover, took active art in several national and international quality control programs. They might be identified therefore as reference units for promoting and controlling the analytical quality in Occupational Hygiene and Toxicology.