Abstract: The present invention relates generally to the field of occupancy detection, and more particularly to an occupancy detection system and a corresponding method suitable for a presence controlled system. A method and system for determining occupancy of a room is provided, in which a signal from a movement sensor positioned in the room is analyzed to detect variations in the signal which correspond to movements of an occupant of the room. The room is determined to be empty if in the received signal a leave pattern is identified. The leave pattern is a predetermined pattern which has been associated with an occupant leaving the room. The method and system provide reliable occupancy detection in more or less static environments like for instance offices, and when utilized in for instance a presence controlled lighting system, the number of frustrating erroneous “switch-off” events of the light in a situation where a room is still occupied by occupants involved in relative still/static activities is then decreased.