 18 out of 32 cases were eligible for analysis. Four patients operated on for benign diseases served as control and 14 patients with operable local gastric adenocarcinoma 4 mucosasubmucosamuscular y 10 serosa lesions were studied. At the beginning of surgery, a 2 x 2 cm. sample from macroscopically normal visceral peritoneum at mesenterium root was carefully obtained, washed with saline and fixed in glutaraldehyde solution. Besides a sample of peritoneal washing fluid was studied to exclude patients with free cancer cells. Peritoneal tissue was fixed during 24 hours and then all samples were evaluated by electronic microscope. 