Esophageal invasion of upper stomach cancer was analized on the resected specimen based on its occurring point and size. The distance of esophageal invasion was calculated by subtracting the distance between the occurring point and esophagogastric junction (EJG) from the radius of the cancer on the preoperative X-ray films. Fifty-six (76.7%) out of 73 resected cancers of the upper stomach invaded the esophagus. The average distance of invasion was 19.8 +/- 12.7 mm; the longest distance was 64.0 mm. The shorter was the distance of the occurring point from the EGJ, the longer was the esophageal invasion. The calculated distance of esophageal invasion of the cancer was correlated significantly with its histological distance (p less than 0.01). The distance of esophageal invasion can be seen with acceptable accuracy on the X-ray films preoperatively, even when the proximal edge of esophageal invasion is not clear on the films.