Endoscopic ultrasonography-guided fine needle aspiration(EUS-FNA) is a useful and relatively safe tool for the diagnosis and staging of pancreatic cancer. However, there have recently been several reports of tumor seeding after EUS-FNA of adenocarcinomas. A 78-year-old man was admitted to our hospital due to upper gastric pain. Examinations revealed a 20 mm mass in the pancreatic body, for which EUS-FNA was performed. The cytology of the lesion was adenocarcinoma, and the stage of the cancer was T3N0M0. The patient underwent surgery with curative intent, followed by adjuvant chemotherapy with S-1. An enlarging gastric submucosal tumor was found on gastroscopy at 28 mo after surgery accompanied by a rising level of CA19-9. Biopsy result was adenocarcinoma, consistent with a pancreatic primary tumor. Tumor seeding after EUS-FNA was strongly suspected. The patient underwent surgical resection of the gastric tumor with curative intent. The pathological result of the resected gastric specimen was adenocarcinoma with a perfectly matched mucin special stain result with the previously resected pancreatic cancer. This is the first case report of tumor seeding after EUS-FNA which was surgically resected and inspected pathologically. Endoscopic ultrasonography-guided fine needle aspiration (EUS-FNA) is a useful and relatively safe tool for the diagnosis and staging of pancreatic cancer. However, there have been several reports of tumor seeding after EUS-FNA of adenocarcinomas. A 78-year -old man was admitted to our hospital due to upper gastric pain. Examinations revealed a 20 mm mass in the pancreatic body, for which EUS-FNA was performed. The cytology of the lesion was adenocarcinoma, and the stage of the cancer was T3N0M0. The patient underwent surgery with curative intent, followed by adjuvant chemotherapy with S-1. An enlarging gastric submucosal tumor was found on gastroscopy at 28 mo after surgery accompanied by a rising level of CA19-9. Biopsy result was adenocarcinoma, consistent with a pancreatic primary tumor. Tumor seeding after EUS-FNA was strongly suspected. The patient underwent surgical resection of the gastric tumor with curative intent. The pathological result of the resected gastric specim en was adenocarcinoma with a perfectly matched mucin special stain result with the previously resected pancreatic cancer. This is the first case report of tumor seeding after EUS-FNA which was surgically resected and inspected pathologically.