The length and weight of gastrointestinal tracts including contents of ten week old male pikas (Ochotona rufescens rufescens) and suncus (Suncus murinus) were measured and they were investigated and compared with those of millardias, ICR-mice and Wistar-rats. The length from the duodenum to the anus of pikas was much longer and the weight from the stomach to the anus was about 16g per 100g of body weight. The weight of cecum was about 7g per body weight and they were heavier than those of other species. The length from the duodenum to the anus of the suncus was short but the weight of the small intestine plus colon and rectum per body weight did not differ from that of other species. The suncus has no cecum but the weight from the stomach to the anus was almost the same as that of rats.