Abstract: A portable, self-contained combination smoke and burglar alarm includes a smoke sensor and a tester switch both capable of energizing of an audible warning device, all contained in a housing adapted for mounting on an interior room surface such as on a wall or ceiling above a door or window. A releasably inserted locking pin retains a spring-biased plunger mounted above a pressure actuable tester switch accessible externally of the housing to maintain the plunger in its cocked condition. A line attached to the releasable locking pin also attaches to an adjacent door or window such that opening of the door or window increases tension on the line which effectively removes the locking pin and releases the plunger to strike the tester button and actuate the alarm.