Based on the gross lesion, a survey of ulcer prevalence was carried out on pigs (3,161 heads) at a slaughterhouse in seoul from April to December in 1989. The pigs stomachs were observed anatomically and classified, according to the presence or absence of foreign bodies. Ulcer prevalence is usually classified according to size of pig farm, ages, and supplied month. The results in the studies were as follows, 1. Fundus followed the highest rate with 28.2%, esophagus with 24.5％ each of cardiac and pyloric part with 7.8% and 4.1％ in cases of gastric mucosa pathological studies examed total 3,161. In the acute ulcer prevalence, fundus follwed with 5.4%, esophagus with 2.6%, each of cardiac and pyloric part with 0.8% and 0.3%. When prevalent frequencies of fundus are compared with cardiac and pyloric part, they have meaning.(P <0.05). 2. In the survey pig of total 3,161, pathological changes of epithelium tissue foliowed 44.0%, erosion(11.5%), chronic ulcer(14.8%), acute ulcer(1.6%), scar formation (1.7%) and perforation (0.9%). 3. In general monthly prevalence rates of gastric lesion are higher in spring and fall than in summer. 4. In the size of pig farms, ulcer showed higher rate at professional farms than raising on the side. 5. When there are more fluid condition in stomach and they are old, the ulcer appeared for more. 6. Foreign bodies in stomach were sand, hairballs, and intestinal worms were detected (1%).