Abstract: Patient bed alarm system (10) is the subject of the present invention. The system (10) includes a plurality of sensors defining interstices (18) of a matrix (16) of such sensors. The matrix (16) is woven into a mat (14) for placement on a bed (12) in which a patient is confined. The presence of the patient's body upon the mat (14) causes various combinations of the sensors to perceive the presence of the patient's body thereon. The particular combinations of sensors sensing the presence of the body is inputted to a first micro computer (20) which discriminates as to the exact location of the patient in view of the exact combination of sensors perceiving the presence of the patient's body. If the combination of sensors actuated indicate an impending vacation of the bed (12) by the patient, an alarm (26, 28) can be actuated by a second micro computer (24) to alert monitoring personnel of the situation.