Abstract: A radioimmunological assay was used to determine the levels of serum gastrin in 35 patientswith adenocarcinoma of the gastric cardia and in 30 health control persons. The mean level of serumgastrin in the patients with carcinoma of the gastric caedia was 191. 4士46. 3pg/ml, and was signifi-cantly higher than that in control group (48. 3士24. 9pg/ml). Noreover, the mean level of serumgastrin was 107. 3士40. 6pg/ml in the patients with lymph node metastasis，in contrast to 49. 3士31" 6pg/ml in the patients without lymph node metastasis. The level of serum gastrin was 113. 7士41. 3pg/ml in the patients in whom the cancer cells have penetrated the mucosal musculature to themuscularis externa，and this value was significantly higher than that (62" 8王37. lpg/ml) in the pa-bents in whom the cancer cells only invaded the mucosal museulature. The mean levels were 92. 4士43. 8pg/ml in the patients with well differentiaved adenocarcinima and 109. 4士51. 3pg/ml in thepatients with poorly differentiated adenocarcinoma,however,the difference was not statistically sig-riificant. It is suggested that measurement of serum gastrin may be a guide for diagnosis and prog-nostic evaluation of carcinoma of the gastric cardia.