With the implementation of a small-caliber panendoscope which was made according to our suggestion, we gradually replaced the conventional barium meal as the first line of the upper gastrointestinal tract examination by panendoscopy after 1976. The efficacy of panendoscopy for the early detection of gastric cancer in our 8-yr experience was investigated. In 910 matched pairs of patients subjected to "screening" fluoroscopy or panendoscopy two and six cases of early gastric cancer were detected respectively. Panendoscopy was superior to fluoroscopy in its sensitivity for detection of gastric cancer (86.4% vs. 80.0%), in its specificity (99.5% vs. 97.0%) and in its low false-positive rate (17.4% vs. 69.2%). After 1976, the detection of early gastric cancer increased year by year. The frequency of early gastric cancer detected by panendoscopy was about three times that of early gastric cancer detected by fluoroscopy (61.5% vs. 21.7% of all cancer). Early cancer located in the proximal third of the stomach and superficial esophageal cancer were detected only by panendoscopy. All gastric cancers that were overlooked by panendoscopy were in the gastric body. How to prevent such overlooking is discussed. In 24,000 panendoscopies we have encountered six complications (0.03%). The cost of panendoscopy and fluoroscopy is 6,500 yen and 11,000 yen respectively.