Background: Endoscopic mucosal resection (EMR) of early gastric cancer (EGC) or gastric flat adenoma has been widely accepted as a useful method due to its minimal invasiveness and satisfactory post-procedure results in maintaining a good quality of life for patients. Aim: The purpose is to define the long-term effect and usefulness of EMR of EGC and gastric flat adenoma. Materials andMethods:We analysed, retrospectively, 101 lesions (73 gastric flat adenoma, 28 EGC) in 96 cases that could be followed-up were analyzed. Follow-up endoscopy examination after EMR was performed at 1, 3, and 6 month in the first year and annually thereafter. Results: 1. The mean follow-up period was 17.7 months (1~). 2. Of the 101 lesions, there were 6 recurrences (5.9%);the mean period was 17.3 months (2~). One of 28 EGC, five of 73 gastric flatadenoma showed recurrence. Among 6 the recurrences, one was detected on the other area of primary EMR site, the other 5 lesions recurred at the primary lesions. 2. With respect to size of lesion and resection method, 16.7% of the recurred lesion were greater than 20 mm in diameter, while 3.4% were 11 to 20 mm and 4.3% were less than 10mm. The recurrence rate tended to be higher in as the size increased (p=0.06). In the lesions which were resected by planned piecemeal, 10% of those lesions recurred (4/40), while 3.3% (2/61) of those lesions recurred in which lesions were resected en bloc(p=0.21). 3. With respect to sex and pathology of primary lesion, there was no difference in the recurrence rate. 4. With respect to location of the primarylesions, the recurrence rate was higher in the lesions of the cardia (50%, p<0.05), compared to the antrum (5.5%), angle (9%) or body (3%). Conclusion: We concluded that the lesions size and location were related to recurrence after EMR, but sex, pathology, and resection method were not related. However, as the size of primary lesions increased rate of piecemeal resection also increased. Background: Endoscopic mucosal resection (EMR) of early gastric cancer (EGC) or gastric flat adenoma has been widely accepted as a useful method due to its minimal invasiveness and satisfactory post-procedure results in maintaining a good quality of life for patients. Aim: The purpose is to define the long-term effect and usefulness of EMR of EGC and gastric flat adenoma. Materials andMethods:We analysed, retrospectively, 101 lesions (73 gastric flat adenoma, 28 EGC) in 96 cases that could be followed-up were analyzed. Follow-up endoscopy examination after EMR was performed at 1, 3, and 6 month in the first year and annually thereafter. Results: 1. The mean follow-up period was 17.7 months (1~). 2. Of the 101 lesions, there were 6 recurrences (5.9%);the mean period was 17.3 months (2~). One of 28 EGC, five of 73 gastric flatadenoma showed recurrence. Among 6 the recurrences, one was detected on the other area of primary EMR site, the other 5 lesions recurred at the primary lesions. 2. With respect to size of lesion and resection method, 16.7% of the recurred lesion were greater than 20 mm in diameter, while 3.4% were 11 to 20 mm and 4.3% were less than 10mm. The recurrence rate tended to be higher in as the size increased (p=0.06). In the lesions which were resected by planned piecemeal, 10% of those lesions recurred (4/40), while 3.3% (2/61) of those lesions recurred in which lesions were resected en bloc(p=0.21). 3. With respect to sex and pathology of primary lesion, there was no difference in the recurrence rate. 4. With respect to location of the primarylesions, the recurrence rate was higher in the lesions of the cardia (50%, p<0.05), compared to the antrum (5.5%), angle (9%) or body (3%). Conclusion: We concluded that the lesions size and location were related to recurrence after EMR, but sex, pathology, and resection method were not related. However, as the size of primary lesions increased rate of piecemeal resection also increased.