A quick coupling, for example of a female type, to be connected with a counterpart, of a male type, comprises, inside a valve body, downstream of an inlet fitting for receiving a pressurized fluid flow (F), a guide and conveying body ( 7 ) having a parabolic cross section, and a plurality of radially outwardly extending ribs, delimiting, circumferentially of the guide and conveying body, a plurality of flow channels communicating with an annular chamber ( 6 ) closed by a valve body ( 3 ).