Abstract: A ventilated seat cushion detachably connectable to a source of forced air within a motor vehicle to provide cooling and heating of an occupant of the seat cushion is disclosed. The present seat cushion is connectable to a source of forced air by a flexible air hose which is in fluid communication with an air intake manifold internally of the cushion that distributes forced air through a series of perforated plastic tubing members. The forced air is discharged through a plurality of vents formed through the outer layers of the cushion so as to be delivered directly to those portions of the seat occupant in contact with the cushion. In one embodiment the ventilated seat cushion is constructed as an after-market device for detachable connection to the heating and/or air conditioning outlets of the motor vehicle. In an alternative embodiment the present seat cushion is permanently integrated into the understructure of the motor vehicle seat at the time of manufacture.