It was studied in global values and octave band, on the L and A scales, the usual noise of three operating-rooms, in two hospitals in São Paulo. The same study had been done with the noises made by the following equipments, that are normaly used in operating-rooms: eletric Valleylab, Emai, Bovie, Burdick bistouries; Takaoka, Narcofolex, Aga, Oftec respirators; Takaoka, Medap, Card, Oftec aspirators; Dremel, Kaltembach und Voigt drills; eletric Bone Stryker Saw and, FUNBEC cardioscopic. It was confronted, yet, the noise made by aparatus of different trade marks, but, with the same functions, like: respirators, aspirators, eletric bistuories and eletric drills. It was stipulated the average additions of the noises made by five equipments that work simultaneously. The results of the tests proved that the noise, in the studied operating-rooms, is inferior of the maximum level preconized for hospitals. The obtained results, permit to conclude that the noise made by the studied apparatus is not sufficient to cause deafness in the components of the surgical team or in the patient, but it is sufficient to cause physiological and psychological alterations in those ones.