Indirubin possess great medicinal efficacy in the treatment of chronic myelocytic leukemia (CML).This study provides a new and reliable method to accurately identify medicinal materials that contain indirubin and discriminate them from their adulterants.High Performance Liquid Chromotography (HPLC) was used to verify indirubin in different organs of medicinal plants including Isatis tinctoria, Polygonum tinctorium, Strobilanthes cusia, and five of their usual adulterants.