Abstract: The present invention discloses an improvement of a mouth-to-mouth resuscitation device characterized in that it has a lower casing and an upper casing separated by a pliable and elastic diaphragm. The elastic diaphragm is upheld by two struts affixed to the lower casing and urged against the bottom of the upper casing to seal any communication between the upper casing and the lower casing and thus preventing air from leaking into said upper casing from lower casing under normal conditions. When the diaphragm is urged by air pressure from the upper casing the portions of the diaphragm not being upheld by the struts will be bent down to allow air to flow into the lower casing. And when the air pressure from said blow-in portion stops, the diaphragm will return to its normally closed portion and seal the upper chamber from the lower chamber.