Abstract: An automatic tubular deadbolt lock assembly having the automatic actuator mechanism enclosed within the tubular housing of the lock. The assembly is dimensioned like a standard tubular deadbolt, to fit within standard borings of present doors. A special quadrant trigger is mounted in and protrudes from the nose of the deadbolt, being pivotal into the deadbolt itself to an inactive recessed position upon opening of the door. With closure of the door, the trigger is cammed and depresses a camming plunger to release a transverse locking pin from engagement with the tubular lock housing, to thereby allow biased extension of the deadbolt from its retracted condition. The trigger can be rotationally reversed to accommodate left hand or right hand door arrangements.