Since 1984, an experimental and clinical study on the relation between PGE and gastric carcinoma has been performed by determining PGE content in the bioptic gastric mucosa and plasma. It is found the PGE content in the gastric mucosa and plasma is increased in all patients with gastric cancer, especially with signet ring cell carcinoma. It is higher in the regional lymph node metastasis than in the early cancer, extensive metastases and normal subjects. The PGE content in the plasma is reduced obviously 7-10 days after operation but is increased markedly in recurrent patients. There is no significant difference in extensive metastases, relapse free and normal subjects. The PGE content in the plasma is significantly higher in gastric carcinoma than in chronic atrophic gastritis, but no difference is present between chronic atrophic gastritis and normal subjects.