Abstract: OBJECTIVE To investigate the effects of Zuogui Pill (ZP) medicated serum on the expressions SPARC during the differentiation of rat marrow mesenchymal stem cells towards chondrocytes.METHODS Mesenchymal stem cells (MSCs) isolated from rat bone-marrow were induced differentiation towards chondrocytes and stimulated with ZP in the meantime. The impact of Zuogui Pill medicated serum on the expression of SPARC mRNA around the induced 0， 7， 14 and 21d respectively was assayed by Real-time PCR. SPARC promoter reporter vector was constructed and transfected into bone marrow mesenchymal cell line. After cells treated with or without ZP for 48h， cell lysates were prepared and assayed for promoter activity using the Dual-Luciferase reporter assay.RESULTS The expression of the SPARC mRNA was significant increased in ZP groups than those in blank or non-ZP group on the induced 21 day (P<0.05). The promoter activity of SPARC displayed a one-fold increasing after ZP stimulation compared to blank group (P<0.05).CONCLUSION Zuogui Pill medicated serum can promote SPARC mRNA expression during the differentiation of rat MSCs to chondrocytes mainly through enhancing SPARC gene transcription activity.