Abstract: A sterile transfer system between a bag and a enclosure suitable for use in the pharmaceutical industry, characterized on the one hand of a first part of a bag having a mouth in the form of a pocket, in which the bottom is constituted by a flexible partition separating the interior spaces of the pocket and the bag and capable of being heat-cut, on the other hand a lock chamber installed at the entrance to the sterile enclosure which includes a fixed part on which the pocket can be mounted, this part presenting a central opening receiving a mobile element constituting the door of the lock chamber, the fixed and mobile parts each being equipped with a heatable blade with closed outline overlapping and joined at their apex in airtight manner when the bag is in the closed state, vacuum outlets being provided for applying the flexible partition by means of suction against the heatable blades and effecting the cutting of it by fusion of the zones which come into contact with the blades.