Objective:To explore the clinical efficacy of recombinant human brain natriuretic peptide (rhBNP) on patients with pulmonary hypertension after mitral valve surgery. Methods:Forty eight patients with postoperative pulmonary hypertension after mitral valve surgery were randomly divided into rhBNP infusion group (group A,n=25) and control group(group B,n=23). Group A received recombinant human brain natriuretic peptide (rhBNP) after treatment,while group B did not. The hemodynamic data were monitored consecutively,and the levels of cyclic guanosine monophosphate (cGMP) and thromboxane A2 (TXA2) were detected pretreatment and after treatment. Results:The mean pulmonary arterial pressure and pulmonary capillary wedge pressure in group A decreased significantly 3 hours,6 hours,and 12 hours,respectively,after treatment,compared to group B (P < 0.05). Pulmonary vascular resistance index in group A decreased significantly 1 hour after treatment,compared to group B (P < 0.05). cGMP in group A increased significantly after the treatment,compared to group B (P < 0.05). TXA2 showed no significant difference within groups and between groups. Conclusion:rhBNP can effectively reduce pulmonary hypertension via increasing serum cGMP level.