[Objective] This study aimed to compare the microstructure between I. in- digotica Fort. and B. cusia （Nees） Bremek. [Method] Microstructure of I. indigotica Fort. and B. cusia （Nees） Bremek. with different sources were compared and analyzed by using digital microscopy. [Result] Comparison result of the microstructure shows that reticulate vessels, single starch granules, multiple starch granules and stone cells are mostly observed in I. indigotica Fort.; pitted vessels, parenchyma cells with small pits, single starch granules and cystolith are mostly observed in B. cusia （Nees） Bremek., which indicated that microstructure of L indigotica Fort. and B. cusia （Nees） Bremek. are significantly different. [Conclusion] Microstructure char- acteristics of I. indigotica Fort. and B. cusia （Nees） Bremek. established in this study can be used to evaluate the quality of these two kinds of Chinese herbal medicines, which also provide scientific basis and methods for comprehensively studying the quality standard of /. indigotica Fort. and B. cusia （Nees） Bremek. Key words Isatis indigotica Fort.; Baphicacanthus cusia （Nees） Bremek.; Microstruc- ture; Quality
