Gastric high grade dysplasia is an important premalignant lesion because of high possibilities of transforming to adenocarcinoma. It is known to be progressed to adenocarcinoma in 60-85% during 4.7 years follow-up period in previous studies. So biopsy-proven high grade dysplasia should be regarded as an early gastric cancer and treated with en bloc resection method like endoscopic mucosal resection (EMR) or endoscopic submucosal dissection (ESD). A repeated endoscopic resection is technically difficult, because of the severe ulcerative and fibrotic change. Gastrectomy can`t save stomach and cause several complications like dumping syndrome or vitamin B deficiency. Wedge resection can make a resection larger than expected and cause gastric stenosis or deformity. Ablative therapy could be an alternative to surgical treatment or repeated endoscopic treatment, but with limited role. A 63-year-old man was diagnosed gastric high grade dysplasia at angle four months ago. He had no symptom and no abnormalities in physical examination and laboratory findings. Abdominal CT didn`t show gastric wall thickening and abdominal lymph node enlargement. He treated with ESD but pathologic report showed horizontal margin involvement. We tried ESD again, but the lesion was diffusely edematous and margins were uncertain. Pathologic report of second ESD also showed horizontal margin involvement. Because it isn`t possible to do ESD due to marked fibrosis and unclear margin, we decided to treat him with laparoscopy-assisted endoscopic full-thickness resection (EFTR). EFTR is a recently discovered method to use endoscope to mark margins of the lesion, resect full-thickness around three-fourths circumference and laparoscope to resect full-thickness around the remaining one-fourths circumference and make the lesion closed. The specimen was measuring 4.2×3.0×1.2 cm in size. Because the final pathologic report revealed high grade dysplasia and focal intramucosal cancer sized 0.8×0.7 cm, we conclude that the lesion was completely resected. As you can see in this case, EFTR can be a great alternative treatment in gastric high grade dysplasia impossible to do ESD.