Background Spleen in Traditional Chinese Medicine (TCM) is not actually the spleen in the anatomic sense designated in western medicine because its functions basically belong to the physiological category of digestive system in modern medicine, and it represents a macroscopic concept of digestion, absorption and nutrition metabolism Spleen deficiency syndrome refers to the clinical phenomena such as hypofunction of digestion, absorption and nutrition metabolism By integrating TCM with modern medicine , this paper is intended to explore the pathological basis of classification of spleen deficiency in chronic gastritis Method By means of optical microscope, scanning electron microscope (SEM), transmission electron microscope (TEM) and histochemical staining, we conducted histopathological and subcellular ultrastructural (nuclei and mitochondrial) analysis of gastric mucosa of 188 patients of spleen deficiency, and that of 42 voluntary blood donors without clinical symptoms Results The gastric mucosa of patients with spleen Qi deficiency (SQD) and spleen yang deficiency (SyangD) could either be affected by organic lesion (type G-occurring on the basis of chronic superficial gastritis (CSG), chronic atrophic gastritis (CAG)) or unaffected (type F-chiefly belonging to functional indigestion); spleen yin deficiency (SyinD) and spleen deficiency with Qi stagnation (SDQS) both occurred on the basis of CSG and CAG; and the degree of mucosa inflammatory cells infiltration, the degree of decrease in glands propria, and the incidence of IMⅡ b in CSG and CAG were more serious than those of G-SQD and G-SyangD, P <0 05-0 01 Conclusion Spleen deficiency syndrome is likely to occur on the basis of organic lesion of gastric mucosa (disease with symptoms of both CSG or CAG and spleen deficiency symptoms), as well as on the basis of inorganic lesion of gastric mucosa (nondisease with symptoms, which is, despite spleen deficiency symptoms, there is no CSG or CAG) Besides, the clinical phenomenon of disease without symptoms (despite CSG or CAG, there is no spleen deficiency symptoms) occurres because of such factors as genetic diathesis and compensation The lesion degree of CSG or CAG and the incidence of IMⅡ b of SyinD and SDQS are more serious than those CSG and CAG of G-SQD and G-Syang D. Background Spleen in Traditional Chinese Medicine (TCM) is not actually the spleen in the anatomic sense designated in western medicine because its functions basically belongs to the physiological category of digestive system in modern medicine, and it represents a macroscopic concept of digestion, absorption and nutrition metabolism Spleen deficiency syndrome refers to the clinical phenomena such as hypofunction of digestion, absorption and nutrition metabolism By integrating TCM with modern medicine, this paper is intended to explore the pathological basis of classification of spleen deficiency in chronic gastritis Method By means of optical microscope, scanning electron microscope (SEM), transmission electron microscope (TEM) and histochemical staining, we conducted histopathological and subcellular ultrastructural (nuclei and mitochondrial) analysis of gastric mucosa of 188 patients of spleen deficiency, and that of 42 voluntary blood donors without clinical symptoms results s The gastric mucosa of patients with spleen Qi deficiency (SQD) and spleen yang deficiency (SyangD) could either be be affected by organic lesion (type G-occurring on the basis of chronic superficial gastritis (CSG), chronic atrophic gastritis (CAG)) or unaffected (type F-chiefly belonging to functional indigestion); spleen yin deficiency (SyinD) and spleen deficiency with Qi stagnation (SDQS) both both on the basis of CSG and CAG; and the degree of mucosa inflammatory cells infiltration, the degree of decrease in glands propria, and the incidence of IMII b in CSG and CAG were more serious than those of G-SQD and G-SyangD, P <0 05-0 01 Conclusion Spleen deficiency syndrome is likely to occur on the basis of organic lesion of gastric mucosa (disease with symptoms of both CSG or CAG and spleen deficiency symptoms), as well as on the basis of inorganic lesion of gastric mucosa (nondisease with symptoms, which is, has spleen deficiency symptoms, there is no CSG or CAG) B esides, the clinical phenomenon of disease without symptoms (despite CSG or CAG, there is no spleen deficiency symptoms) occurres such of as factors as genetic diathesis and compensation The lesion degree of CSG or CAG and the incidence of IM Ⅱ b of SyinD and SDQS are more serious than those CSG and CAG of G-SQD and G-Syang D.