Abstract: A method of assigning network addresses for ventilators (3, 4, 5) in a network. Each ventilator (3, 4, 5) has a unique serial number in a serial number memory (8) and a network address in an adjustable network address memory (9). A control unit (1) automatically assigns network addresses to a plurality of ventilators (3, 4, 5). To begin with, all ventilators are assigned an identical start-address as network address, and serial number queries with a serial number mask are sent to the start-address. The serial number mask is comprised of definite and indefinite positions, and the ventilators (3, 4, 5) respond to the serial number mask subject to their serial number. The control unit (1) assigns unique network addresses to the ventilators (3, 4, 5) independently of the responses and/or modifies the serial number mask for further serial number queries.