The invention refers to a medical system comprising a first subsystem with a first connection portion (7), and a second subsystem with a second connection portion (12). The invention also refers to a device and a method for connecting the subsystems to each other. One of the subsystems contains a fluid. The connecting device is adapted to connect the subsystems to each other to permit transport of the fluid from one of the subsystems to the other subsystem. The device comprises a container (21) enclosing an inner space. A substantially sterile atmosphere is provided in the inner space. The container receives the first connection portion and the second connection portion in the inner space. A mechanism is provided for connecting, from outside the container, the first connection portion and the second connection portion to each other in the inner space.