It was in 1983 when we started to apply YAG laser to do experiments on animal and fresh internal organs off the body to confirm its effectiveness. Then we started to use it in clinical practice. Up to October 1995, in the twelve years, we treated 1075 cases, 2574 person times. Seven-hundred-seventy-nine cases of various esophagostenosis. Four-hundred-fifty-six of them were malignant stenosis, 295 anastomostenosis, 15 stenosis after radiotherapeutics, 7 corrosive anastomostenosis, 6 inflammatory anastomostenosis, plus we cured 5 cardia losses of relax, and 241 polyps in the alimentary canal. Among the 2154 polyps cured, 6 were that of esophagus, 6 that of cardia, 25 that of stomach, 10 that of duodenum, 194 that of large intestine. In addition, we treated 15 alimentary canal bleeding and 35 malignant colon and tectum cancers. Our experience in laser operating on the coelom has become richer and richer. The methods we used are being widened. The range of our laser application is being enlarged. We have gained our own experience in preventing complications and keeping the endoscopy from being damaged. The cure rate of the non-malignant had raised up to 98.7%. Cure rate of the malignant had raised up to 91%. The alimentary canal polyps can be cured perfectly. It is hard to tell whether YAG laser or high frequency electroresection has the advantage over the other. Besides, this paper is going to put forward several questions to discuss.