The microbiology quality control importance is emphasized and some particular problems that quality control presents in microbiology are also indicated. There are two types of microbiology quality control as well as for hematology and chemical chemistry: collective quality control, between more laboratories, and individual quality control, in the sphere of each laboratory. A.M.O.I. (Associazione Microbiologi Ospedalieri Italiani) and I.S.V.T. (Istituto Sieroterapico Vaccinogeno Toscano) Sclavo collaborating, have organized a collective quality control between laboratories of different hospitals during the year 1974 and 1975. The results of this control are reported. Although preliminary, they indicate practical importance of microbiology control. During 1975, in fact, the pathogens isolated have been in high percentage than 1976. At last, the future quality control's program aiming at methods's standardization and technical, methodical instructions is indicated.