The author contends one can not plan an operatief theatre and its organization, if it is dissociated from its immediate dependencies, entrances and exists. a) The necessity of the following dependencies is discussed: 1. an anesthetic room forming a sas between the entrance hall for the patient and the operating room that makes possible the preop. preparation; 2. an area where the surgeons may prepare, corectly ventilated and reserved to the entrance of the surgical team; 3. a reserve of sterile equipment in immediate contact with the operating threater; 4. a disposal area for the linen and soiled material and that may serve to the transfer of the patient after the operation, given the wastes be evacuated in thermosealed bags. b) The circuits of the personel is then considered with a study of the one way cloak-rooms, and an example is given. Then comes the introduction in these circuits of the so-called septic operating room and of room for decontamination of instruments that can be superimposed with the place of evacuation of the equipment. In conclusion, the author mentions the evacuation of atmospheric particles released in the operating theatre and the methods of improving asepsis. He suggests the surgeon be very critic concerning the techniques proposed by the advertising.