An oil separator assembly for separating and recovering oil droplets from compressed hot refrigerant gas circulating in a refrigeration system comprises a hollow metal tank having a chamber in which a hollow cylindrical fine-mesh filter element is vertically mounted. The filter element has a hollow cylindrical bore open at its upper end and closed at its lower end. A gas/liquid inlet pipe extends into the top of the tank and communicates directly with and extends into the upper end of the filter element bore. The inlet pipe has a passage therethrough defined by a wall. A gas outlet pipe extends into the top of the tank and communicates directly with the chamber to expel gas separated from the oil by the filter element. An oil outlet port extends into the bottom of the tank to allow for drainage of oil separated from the gas by the filter element. A deflector in the form of a flat metal strip twisted into a spiral shape is mounted in the inlet pipe passage in contact with the wall thereof to cause the incoming gas/oil mixture to impinge forcefully against the bore wall whereby oil droplets coalesce into larger drops and to expedite movement of the gas and larger drops through the filter element.