This study investigated the relationship between the gastric mucosa, gastric emptying and the peroral iron loading test in gastric ulcer and gastric cancer cases. The gastric mucosa in gastric ulcer cases was similar to that in gastric cancer cases. Gastric emptying in the M portion was delayed more than in the C and A portions as well as in the control group. In both early and advanced gastric cancer cases, gastric emptying was delayed slightly more than in the control group. The results of the peroral iron loading test showed that the serum iron level in the gastric ulcer cases in the active stage increased more remarkably than in the healing stage. In early gastric cancer cases the results of the peroral iron loading test were similar to those of the gastric ulcer cases. In advanced gastric cancer cases, the quantity of the serum iron did not increase significantly. In both gastric ulcer and gastric cancer cases, the quantity of serum iron in the cases with anemia was significantly increased. In both gastric ulcer and gastric cancer cases, negative correlation was recognized between serum ferritin and an increased quantity of serum iron. In gastric ulcer cases on the M portion, positive correlation was recognized between the increased quantity of serum iron and gastric emptying. In both gastric ulcer and gastric cancer cases, the increased quantity of serum iron in cases with severe atrophic gastric mucosa was more significant than in those with mild atrophic gastric mucosa.