The purpose of this study was to examine and compare the clinical outcome of endodontic microsurgery after 1 year of follow-up and over a period of 4 years.The database of the Department of Conservative Dentistry, Yonsei University, Seoul, South Korea, was searched for patients who had undergone endodontic microsurgery and had been evaluated 1 year after surgery and over a period of 4 years. Two examiners independently evaluated the postoperative radiographs taken 1 year after surgery and over a period of 4 years using Rud's criteria. To analyze and compare the success rate based on the observation period, the McNemar test was performed with a significance level of 0.05.The study included 115 cases. Using Rud's criteria, the overall success rate of cases with 4 or more years of follow-up was 87.8% compared with 91.3% at 1 year of follow-up. There was no significant difference between the follow-up periods (P = .344).There was no significant difference in the clinical outcome after endodontic microsurgery when comparing 1-year follow-up periods with longer follow-up periods.