The present invention relates to a ventilation system for an operating room. The operating room comprising a surgical Area (1), where the patient and surgical personnel (SI) are positioned during surgery, an anesthetics Area (3), where the anesthetics personnel (S3) are positioned during surgery, and a door (8) to an outside of the operating room. The ventilation system comprises a plurality of first exhausting units (6) positioned in the proximity of at least two corners of the operating room, and a second exhausting unit (7) positioned with its center point (7c) at least 2 meters above a floor level and within 3 meters from a center point (8c) of an upper frame of the door (8). The second exhausting unit (7) is configured to exhaust more air per time unit than any one of the first exhausting units (6) individually.
