Abstract: Process and installation for the ultraclean continuous transportation of erial from a point P to a point P' within a bacteriologically controlled zone by a conveyor. The conveyor is continuously covered from upstream of point P with respect to the direction of travel of the conveyor, to downstream of point P', with a solid covering whose surface adapted to come into contact with the material is sterile. The material is deposited at point P on the covering, and the transported material is removed from contact with the solid covering at point P'. The path of the material is enclosed at least between points P and P', and a bacteria-free atmosphere is established in this enclosed path.