Objective To investigate the anatomic and histologic characteristics of the digestive tract of EM>Canis lupus/EM>and EM>Canis familiaris/EM> and types, regional distributions and cell densities of gastrointestinal endocrine cells in various parts of their digestive tract, in order to clarify morphology and cytohistology mechanism of their different feeding habits. Methods Six wolves and six domestic dogs have been tested, using morphological observation and paraffin sectioning to compare the anatomic and histologic characteristics of the digestive tract; using immunohistochemical techniques to compare the types, regional distributions and cell densities of gastrointestinal endocrine cells in various parts of their digestive tract. Results From the comparison of the anatomic and histologic characteristics of the digestive tract between EM>Canis lupus/EM> and EM>Canis familiaris/EM> we found that wolves have shorter in total length and lighter in total weight than that of domestic dogs, especially colon. They also possessed much thinner in cardiac glandular region and oesophagus and cardiac mucosa but thicker in fundus gland region, jejunum and colon canal wall and large intestine mucosa. From the comparison of the characters of endocrine cells we could find that, most of their endocrine cells have the similar regional distributions except pancreatic polypeptide (PP) positive cells and substance P (SP) positive cells.Conclusion The comparison between EM>Canis lupus/EM> and EM>Canis familiaris/EM> indicate that different feeding habits have caused several anatomical and histometical changes of their digestive tract, but