Abstract: A separator device for a system for recirculation of blow-by gases of an internal-combustion engine comprises an elongated casing defining a separation chamber with an inlet at one end, for communication with the crankcase, an outlet at the second end, for communication with the intake system of the engine, and an end wall with at least one draining sump for draining the liquid separated in the separation chamber for return of the separated liquid into the crankcase. Associated to said inlet is an open/close element with flexible flap that opens when the crankcase is in overpressure with respect to the separation chamber, whereas associated to each draining sump is a membrane open/close element that, in the aforesaid condition of overpressure, closes, whereas, when the crankcase is in negative pressure, opens, enabling return of the liquid separated and collected inside each draining sump into the crankcase.