The invention relates to a device for washing the nasal cavities with a nebulized treatment liquid. It comprises a base body, a atomizer chamber containing a washing liquid, means for nebulizing the liquid in said chamber and dispensing the atomized liquid to the nasal cavities for washing and a chamber for collecting the return liquid and catarrhal matter from the nasal cavities. The atomizer chamber (12) and collection chamber (13) are positioned side by side above the base body, and the collection chamber communicates with a dispensing exit of the atomized liquid to the nasal cavities. The two chambers may be defined each by a respective element or by a single piece.