Objective To assess referral cases for root canal therapy to provide clinical evidence with establishment of referral system. Methods A questionnaire was designed to collect 312 cases(355 teeth) referred to Department of Conservative Dentistry and Endodontics, West China School of Stomatology, Sichuan University for root canal therapy from April to June in 2011. The questionnaire consisted of questions such as age, gender, occupation, general disease and medical histories of patients, sources. Difficulty of treatment before therapy and reasons for referral were evaluated. Results In 355 referral teeth, the most were mandibular first molars(17%), the greatest percentage of reasons were calcified root canals(30%), the second was root canal retreatment(24%). 72% of teeth belong to the complicated difficulty(Class Ⅲ), while 7% were listed as the uncomplicated difficulty(Class Ⅰ). No significantly difference from different sources was found(P=0.9). Conclusion Establishment of referral system needs cooperation with every dentist. Difficulty of cases for root canal therapy before treatment should be first evaluated to treat or to refer. Referral cases for root canal therapy should be treated by endodontist of corresponding level according to the difficulty.