0.05) in plasma ET, CGRP levels and PaO2 was observed among those groups in convalescence, mild bronchopneumonia, and normal control. There was a significantly negative correlation between plasma ET and CGRP levels (r = -0.65, P<0.01) in the critical stage of heart failure and also the same correlation between plasma ET and PaO2 (r = -0.66, P<0.01). Conclusion: The finding suggest that the increase of plasma ET level and decreased of plasma CGRP may be play an important role in the pathogenesis of infants with acute congestive heart failure associated with severe pneumonia. The causes of plasma ET level increased probably were related to the decrease of plasma CGRP level and the decrease of PaO2. " v:shapes="_x0000_s1026">0757