AIM: To explore the interventional effects and mechanism of in vitro cultivated Calculus Bovis compound preparation (ICCBco) on pulmonary lesions in portal hypertensive rabbits with schistosomiasis. METHODS: The experimental group included 20 portal hypertensive rabbits with schistosomiasis treated by ICCBco. The control group included 20 portal hypertensive rabbits with schistosomiasis treated by praziquantel. The morphological changes of the pulmonary tissues were observed under light and electron microscopy. The expression of fibronectin (FN) and laminin (LN) in the lung tissues was analyzed by immunohistochemistry. RESULTS: Under light microscope, the alveolar exudation in the lung tissue was more frequently observed in the control group, while the alveolar space was fairly dry in the lung tissue of ICCBco group. Under electron microscope, more alveolar exudation in the lung tissue, and more macrophages, alveolar angiotelectasis and the blurred three-tier structure of alveolar-capillary barrier could be seen in the control group. In ICCBco group, fibers within the alveolar interspace slightly increased in some lung regions, and the structure of type 1 epithelium, basement membrane and endodermis was complete, and no obvious exudation from the alveolar space, and novascular congestion could be observed. There was a positive or strong positive expression of FN and LN in the lung tissue of the control group, while there was a negative or weak positive expression of FN and LN in ICCBco group. CONCLUSION: ICCBco can effectively prevent pulmonary complications in portal hypertensive rabbits with schistosomiasis by means of improving lung microcirculation and lowering the content of extracellular matrix. (C) 2010 Baishideng. All rights reserved.