Abstract: Immunohistochemical and histochemical techniques were used to observe the endocrine cells of induced intestinal carcinomas and adjacent mucosa in 41 rats. The results showed that endocrine cells were present in the carcinomas, the distributions of endocrine cells were similar in each histologic type of carcinoma and adjacent mucosa. This might be closely related to the environments of carcinogenesis. The discrepancy between the distribution of argyrophil cells and irSer cells revealed that argyrophil positivity might be correlated with other factors besides Ser and monoamines.