In order to decide on a treatment strategy against gastric cancers, an accurate preoperative evaluation of the depth of cancer invasion is essential. Preoperative endoscopic diagnosis of the depth of invasion was compared with pathological results of the resected specimen in 206 early gastric cancers and 32 early-like advanced gastric cancers. The endoscopic distinction between early and early-like advanced cancers was correctly made in 83.6% of the cases. Among the early gastric cancers, mucosal and submucosal invasion was correctly presumed in 71.9% of the cases. When the tumor was an elevated type, or located in the antrum, the endoscopic diagnosis tended to be deeper than the true depth. The size of tumor contributed little to the depth diagnosis. Pathomorphological changes on the tips of converging folds were the important clue for diagnosing depth.