Chick embryos (72hr) were heat shocked in a water bath or exposed to continuous wave ultrasound. After exposures, embryos were labeled with 35S-methionine and the proteins separated by SDS-PAGE. Heat-treated embryos showed the enhanced de novo synthesis of three proteins that demonstrated a dose dependent response to temperature and exposure duration. Western blots probed with monoclonal antibodies against heat shock proteins (hsp) and glucose regulated proteins (grp) identified these proteins as hsp25, hsp70, and grp94, respectively. Ultrasound treatment produced an increase in embryonic temperature and induced the synthesis of the same three proteins but at temperature/time thresholds lower than required by heat treatment alone. Preliminary cinephoto-analysis demonstrated that the ventricular shortening fraction was decreased by heat at a temperature of 45°C, but was unaffected at lower temperatures. However, shortening fraction was decreased by ultrasound at intensities of 100, 250, and 500 mW/cm2. These data indicate that ultrasound can produce changes in stress protein synthesis and cardiac function that are not induced by direct heating to comparable temperatures.