A spray gun for spraying paints and similar viscous media that can be propelled pneumatically, comprising a gun housing for accommodating components of the spray gun that effect propulsion, mixture and/or metering, a handle projecting from the gun housing, and a reservoir tank removably attached to the gun housing for holding the medium to be processed, with the housing of the spray gun provided with an air guidance duct through which the compressed air responsible for atomization flows to an atomizer nozzle, wherein surfaces of the air guidance duct and/or atomizer nozzle, and/or an air cap, which come into contact with the stream of compressed air, or are wetted, are provided wholly or in part with a structured surface in the form of indentations and/or protrusions worked into the surfaces.