BACKGROUND: Pulmonary hypertension induced by alternation of pulmonary function and structure is the prerequisite of pulmonary-cardiac disorder. Chinese herb, fenxin mixture(FXM) reduces effectively pulmonary hypertension, but the mechanism on which has not been completely explained yet.OBJECTIVE: To comp are the reversal effects between feixin mixture and nifedipine on vascular remodeling in rats with pulmonary hypertension.DESIGN: Randomized controlled experimental study in which experimental animals are taken as the objects.SETTING: Nursing department of affiliated hospital of a medical university;a medical college affiliated hospital and department of traditional Chinese medicine of a provincial hospital.METHODS: Monocrotaline(MCT) (50 mg/kg) was used to duplicate pulmonary-cardiac model in rats. Totally 60 Wister male rats were randomized into 6 groups, namely normal control group, model group, FXM groups of low, middle and high dosages successively and nifedipine group, 10 rats in each group. Since the 14th day of modeling, the corresponding medications were administrated with gastric infusion, continuously for 8 days. After the rats sacrificed, the special staining collaborating with pathological image analysis was used to determine the measurement alternations on path-morphology of pulmonary small artery.wall square(VWS)/total vessel square(TVS), cavity square(CS)/TVS of pulmonary small artery in rats of every group.RESULTS: Both feixin mixture and nifedipine alleviate pulmonary vascular remodeling remarkably( P ＜ 0.01 ), of which, the effect was the best in feixin mixture group of high dosage. But, the every index in experimental groups had not recovered to the level in normal control group completely.CONCLUSION: Feixin mixture reverses partially the remodeling of pulmonary vascular structure and reduces effectively pulmonary hypertension.