An inertial particle separator for an aircraft engine inlet, including inlet, intermediate and bypass ducts. The intermediate duct extends generally transversally from the inlet duct to the engine inlet, and communicates with the inlet duct adjacent its downstream end. The bypass duct extends downstream from the inlet duct and intermediate duct, and defines an outlet communicating with the environment of the engine. A wall of the intermediate duct intersects a wall of the inlet duct on an engine side of the wall of the inlet duct. The engine side of the wall of the inlet duct defines an engine-side inlet air flow line of the inertial particle separator. A wall of the bypass duct intersects the wall of the intermediate duct closer to a central axis of the engine than an extension of the engine-side inlet air flow line into the bypass duct.