Abstract: OBJECTIVE To develop a biotransformation process to improve the medicinal value of the Chinese herb Sophorae Fructus by converting sophoricoside and other glycosides into genistein. METHODS Sophorae Fructus was treated by biotransformation using crude enzyme from Rhizopus oryzae LJH3. The effects of substrate-enzyme solution ratio, pH, particle size of substrate and conversion time on improving the content of genistein in Sophorae Fructus were investigated. RESULTS The content of genistein in Sophorae Fructus was significantly improved after it was treated with crude enzyme from Rhizopus oryzae LJH3. The optimum biotransformation conditions were as followings:substrate-enzyme solution ratio 5:100, pH 5.0, particle size of substrate 0.2 mm, temperature 30℃ and time 32 h. Under these conditions, the content of genistein in the biotransformed Sophorae Fructus increased to 36.3 mg·g^-1, which was 14.5 times higher than that in the untreated one. CONCLUSION The process by in situ biotransformation of Sophorae Fructus using crude enzyme from Rhizopus oryzae LJH3 has the advantages of simple operations and high productivity, which shows the potential application in the pharmaceutical industry.