Here after are reported all the results obtained from an interlaboratory quality control program performed in Tuscany in 1973 and in 1974. In 1973, 35 hospital laboratories partecipated to the program, while in 1974 the partecipating laboratories were 79: hospital's, private's and of public bodies. The results obtained in the program performed in 1974 were less satisfactory of those obtained in 1973 and showed the need of repeating such programs in order to improve the operating efficiency of laboratories.