Disclosed is a pet patio which is easily mountable in a window of a dwelling or other enclosed area. Access in and out of the patio is gained by the pet by traveling through a series of flaps. The enclosure area of the patio is substantially apertured and transparent on its sides and the floor. Its top includes an optionally transparent roof which is not apertured so that it deflects rain or other elements. Because the patio walls are substantially apertured, the pet is able to enjoy a near outdoor experience while at the same time the HVAC conditions within the room and dwelling are not significantly affected because the outdoor enclosure is sealed off by multiply-flapped corridor.