The purpose of this research was to investigate effects of Bambusae Caulis in Liquamen (BCL) on the synthesis of basement membrane proteins during proliferation and differentiation of 3T3-L1 cells. BCL has been used to relieve the cough and asthma, and remove phlegm in traditional oriental medicines. In recent years. it was studied for its antiinflammatory, antiallergenic. immune-modulating and anticarcinogenic capabilities. We have previously observed that glycyrrhizin stimulates the adipose conversion of 3T3-L1 cells. To investigate effects of BCL on the basement membrane proteins during proliferation and differentiation of 3T3-L1 cells, we have analyzed synthetic amounts of basement membrane components such as type IV collagen and BM40. BCL stimulated the synthesis and secretion of type IV collagen from both 3T3-L1 preadipocytes and adipocytes. The synthesis and secretion of BM40 was not affected by BCL. The continuous addition of BCL markedly stimulated cell growth and increased cell density. These results suggest an important role for type IV collagen in adipocyte differentiation.