Ulcer size, age, sex, alcohol and analgesic intake and cigarette consumption were studied in relation to the site of the ulcer in 215 patients with chronic gastric ulcer, of whom 96 were initial and 115 recurrent ulcers. Ulcer site was classified into upper (U), middle (M) and lower (L) thirds of the stomach, on X-ray films of air-contrast barium studies. The ulcers were situated in the upper third in 37 patients (17%), middle third in 90 patients (42%) and lower third in 88 patients (41%), i.e., significantly more in M and L compared to U (p less than 0.001). 135 ulcers were on the lesser curve (63%) with more in L and M compared to U (p less than 0.0005). Posterior wall ulcers accounted for 29.3%. Ulcers were smallest in L (mean 28.8 mm2) compared to those in M (mean 66.1 mm2) and U (mean 64.4 mm2) (p less than 0.001). Mean size overall was 49.0 mm. The mean age of the patients was 58.8 years with no significant differences in age between U, M and L (p greater than 0.9). The M/F ratio in the whole series was 0.6 which varied with ulcer site, being 0.3 in U (differing significantly from the whole series, p less than 0.05), 0.4 in M and 1.2 in L (significantly different from the whole series, p less than 0.01) and from U (p less than 0.01). Initial ulcers did not differ from recurrent ulcers except in women where initial ulcers were more common in M and L, whereas recurrent ulcers were more commin in U. The independent variables, namely, alcohol and analgesics (with the exception of smoking), were not determinants of ulcer site, size or position once the patients were segregated by sex. In men only, there were interactions between L and lesser curve site (p less than 0.004) and L and smoking (p less than 0.03).