Objective: To explore the relationship among gast ri n, somatostatin and pathogenesis of spleen deficiency syndrome (SDS). Me thods: The changes of gastrin and somatostatin in body fluid and tissues were measured by radioimmunoassay. G cells (gastrin cells) and D cells (s omatostatin cells) of gastroduodenal mucosa were analyzed with polyclonal antibo dy to gastrin and somatostatin, immunohistochemical technique and Quantimet 500 image analysis system. Sijunzi decoction (四君子汤, SJZD) was chosen for counter -co nfirmation of syndrome. Results: The levels of gastrin in plasma, gastric juice, intestinal juice, gastric antrum, duodenum and hypothalamus of e x perimental SDS were significantly lowered and somatostatin markedly higher than the control group, which was improved and even better than spontaneous recovery group after prevention and treatment with SJZD (P<0.05). The count of G cell s and D cells reduced (P<0.05), the area of D cells declined (P<0.05), but m ean grey of G cells elevated (P<0.05) and ratio of the count and area on G/D also in crea sed (P<0.05) in experimental SDS, which was improved and even better than sp onta neous recovery group after prevention and treatment with SJZD (P<0.05). Con clusion: The study confirmed that disturbance of relationship betwee n gastrin and somatostatin would lead to gastrointestinal disorder, which was on e of important causes for pathogenesis of SDS.