The invention includes a bag system for collecting a biological fluid, in particular blood. The system includes a device for collecting the fluid which is in fluid communication with at least one fluid collection bag, and a device for sampling the fluid to be collected which includes at least one sampling receptacle. The sampling device includes a device for transferring the fluid from the bag system into the sampling receptacle or receptacles, in which the transfer device is provided with a device for associating the receptacle or receptacles. The transfer device may be arranged to allow the support of the receptacle or receptacles in a standby position, the guidance of the receptacle or receptacles to a transfer position and, after transfer, the dissociation of the receptacle or receptacles from the bag system.
