Abstract: A damper structure for a clothes dryer vent is disclosed. The damper structure comprises a support member adapted to be inserted inside the dryer vent adjacent the inside wall of a house, and a damper plate mounted on the support member, so as to form a closed air space between the damper plate and the regular closure damper of the dryer vent for minimizing heat losses through the dryer vent. In order to fit a dryer vent of circular cross-section, the damper structure comprises a central damper element hinged at the top of the support structure and two lateral damper elements hinged one on each side of the central damper element for allowing full opening of the damper plate into the tubular dryer vent.