The invention relates to a stir system (1) for stirring a liquid in a vial (5). The system is provided with a top (3) for at least partially closing the vial (5) and a stirrer (9) rotatable mounted in the top. The stirrer extends from the top into the vial and the stirrer is being connected with a magnet (11), which is rotatable during use by a rotating magnet field so as to rotate the stirrer in the vial. The system is further provided with a holder (30) for holding the vial (5) and a cover (31) for covering the vial in the holder.