A breathing tube system for connection to a respirator (2), which is provided with a tube heater, avoids a local increase in temperature during the heating of the tube (4, 7). Resistance wires (9, 10) are connected to one another on the breathing tubes (4, 7) in the form of a series connection and are contacted at the respirator (2) in the area of an inspiration port (3) and of an expiration port (6).