Endoscopic and histopathological findings were compared in 74 patients with gastric cancer infiltrating the lower esophagus who had undergone gastrectomy to evaluate mode of esophageal infiltration. There were no early cancers. Cancer infiltration modes were histopathologically broken down into three types: superficial, whole layer, and deep layer. Endoscopic findings were broken down into five types for proximal infiltration. Endoscopy used for histological evaluation frequently revealed the protruded type to be whole layer and had a highly accurate diagnosis rate (94%); it revealed the histology of the other four types to be primarily superficial. Extent of cancer invasion was underestimated in giant-rugae tumors (40%), as endoscopy could barely detect the small nest of esophageal infiltrations. Lugol staining was useful in preventing underestimation. For flat cancer, which is poorly demarcated and is often accompanied by vascular invasion, preoperative evaluation is very difficult, requiring preoperative examination of a frozen section taken from the proximal edge of resected specimen.