In this study, 857 teeth having undergone nonsurgical root canal treatment (NSRCT) in Taiwan in 2000 were evaluated during a 5-year follow-up period for first untoward events and reasons for tooth extractions. First untoward events occurred in 83 (9.7%) teeth during this follow-up period, and nonsurgical retreatment was performed for 20 (24.1%), 4 (4.8%) received apical surgery, and 59 (71.1%) were extracted. By the end of this 5-year follow-up period a total of 64 (7.5%) teeth had been extracted. There were 65 reasons for tooth extraction given by the 56 performing dentists who responded to the extraction reason questionnaires; 6 (10.7%) were attributed to endodontically related diseases, 15 (26.8%) to periodontal diseases, 26 (46.4%) to large decay or unrestorable tooth, and 18 (32.1%) to tooth fracture. The conclusion was that 7.5% of the NSRCT teeth were extracted by the end of the 5-year follow-up period, and only 10.7% of these teeth were extracted as a result of endodontically related diseases.