Abstract: A reusable grease filter for installation in an exhaust system for restaurant cooking equipment and the like comprising a frame adapted to be fixedly mounted in an exhaust system opening; louvers positionable within the frame having a plurality of discontinuous overlapping louver surfaces extending generally transversely of an exhaust system airflow direction and providing a plurality of tortuous air passages, whereby passage of flame through the grease filter is substantially blocked by the transversely extending overlapping louver surfaces, and whereby grease and other airborne particles are removed from exhaust air; and brackets fixedly mounted on the frame for stably holding the louvers in a predetermined position and for enabling rapid removal and reinstallation of the louvers in the frame for facilitating cleaning of the louvers. Specific structure of the frame, louvers and brackets which enables these functions is described.