Improvements in the endoscopic evaluation and management of gastric cancer have made it possible to determine the depth of invasion during endoscopic examination. The aim of this study was to elucidate the differences between early gastric cancer (EGC) that resembles advanced gastric cancer (AGC) and AGC that resembles EGC.We retrieved cases of EGC-like AGC and AGC-like EGC from consecutive gastric cancers that had been completely resected. The endoscopic diagnoses and clinicopathological findings were analyzed.AGC-like EGCs were located mainly in the distal part of the stomach, whereas EGC-like AGCs were located mainly in the proximal part of the stomach (p<0.001). Sixty percent of AGC-like EGCs were moderately differentiated adenocarcinomas, while 64% of EGC-like AGCs were poorly differentiated adenocarcinomas (p=0.015). According to Lauren's classification, 68% of AGC-like EGCs were intestinal type, whereas 71% of EGC-like AGCs were diffuse type (p=0.020).AGC-like EGCs predominate in the distal part of the stomach, while EGC-like AGCs predominate in the proximal part. When evaluating the depth of a gastric cancer, care should be taken not to underestimate measurements in proximal gastric cancers since they tend to be poorly-differentiated adenocarcinomas, in Lauren's diffuse type, and invade deeper than their endoscopic appearance might suggest.