Abstract: A manikin for practicing artificial respiration by the mouth-to-mouth or mouth-to-nose method and comprising an inflatable lung element, a chest element and a head element having a cavity containing a replaceable bag surrounded by an elastically expandable cover having a predetermined internal volume in its state of rest, the bag having an air inlet which is airtightly connected with a replaceable mouth and nose element and the cavity in the head element being connected with the lung element through an air duct. The manikin does not malfunction in case of a leakage in the secondary air system.