Abstract: A ventilator for air ventilation between a delimited space and the outside air. Extending through the ventilator is a connecting passage (4) which is divided into a plurality of passage sections (10) which are delimited from one another by means of at least one outer wall portion (7/20/32) and partitions (8) which are directed symmetrically with substantially the same length outwards from the central longitudinal axis (9) of the connecting passage (4). The sections are adapted to maintain communication between the outside air and said space and comprise in their outer ends, facing the outside air, an outer opening (13) and in their inner end, facing the space, an inner opening. The outer openings are directed sideways in relation to the longitudinal axis (9) of the connecting passage (4) so that the openings are distributed over the periphery of the ventilator.