An automatic valve for milking installations, comprising a substantially cylindrical hollow body (11) internally defining a chamber (29) for milk passage, which chamber has an axial inlet duct (15) and a radial outlet duct (19) and is provided with a shutter (31) that is axially displaceable between a closure configuration, in which milk passage through the chamber (29) is prevented, and an opening configuration, in which milk passage through the chamber (29) is enabled, wherein said shutter (31) has a shaped impact surface (45b) for guiding the milk flow impinging on said shutter when entering the valve and for imparting a rotary motion to the milk entering the valve, until generating a cyclone effect on the milk flow, which effect is kept as far as along the discharge duct (19).
