Abstract: A pet door for installation in an opening through a dwelling barrier with a frame having a rectangular portal therethrough in which an insulated movable closure is suspended to swingingly pivot intermediate the top edge and lateral midline of the closure. A resiliently flexible seal is mounted around the entire perimeter of the closure to sealably engage the rectangular portal of the frame. A selectively operable latch is carried on the closure to restrict movement of the closure within the portal of the frame.