Questionnaires were distributed to the responsibles and to the dependents of structures with high turnover of people, to have informations about numbers and typology of instruments, habits of dependents and type of cleanings. In these structures, microbiologic quality of air and of informatic instruments' surfaces were evaluated and efficacy of treatment with some products of cleaning and sanification was verified. Air microbiological contamination was comparable to that found in other similar researchs. Fecal contamination indicators were not found on instruments' surfaces, both before, and after treatment; in 8 cases (3%) Staphylococcus aureus was isolated and in 6 cases (2%) species of not pathogenous staphylococci were isolated. At the beginning of the working day, mean values of total aerobic bacterial count at 22 degrees and 37 degrees, were low, settled to zero after treatment and increased progressively during the week. Infective risk for workers can be considered insignificant because of low microbiological contamination. Specific sanification products seem not to be necessary, since common products of cleaning have the same efficacy.