Pulmonary hypertension (PH) is a descriptive name for abnormally elevated pressures in the pulmonary vasculature, which seriously affects the quality of life and survival of patients. Currently, no effective drugs treatment was used in patients with pulmonary hypertension due to acute exacerbation of lung disease. Recombinant Human Brain Natriuretic Peptide (rhBNP)was approved in 2001 for use in patients with acute heart failure on the basis of studies showing a reduction in pulmonary-capillary wedge pressure(PCWP) and pulmonary arterial pressure (PAP) and improvement cardiac output (CO) . Thus, the study was designed to administer rhBNP as a continuous infusion for 24 hours on pulmonary hypertension of acute exacerbations of chronic pulmonary disease monitoring by Swan- Ganz catheter. Each patient was studied on two occasions (6 hours apart). One occasion the subject received rhBNP 1.5ug/kg IV bolus followed by an infusion of 0.0075ug/kg/min for 24 hours; other occasion the subject received IV placebo bolus followed by a placebo infusion for 24 hours .these were administered in random order in double blind fashion.