Objective　To study the CT image features of transverse mesocolon (TM) involvement by pancreatic carcinoma based on the anatomy.　Methods　(1) 4 patients, underwent the upper abdominal surgery and without transverse mesentric diseases were selected and observed. (2) CT images of 64 cases of pancreatic carcinoma with TM involvement were reviewed retrospectively. Emphasis was placed on the follows: (1) the anatomical relationship of TM and pancreas, and the course, distribution and attachment of TM's vessels. (2) The size, shape and location of the mass, and the appearance, density, vascular involvement of the TM, the lymph nodes in the TM and the extent of the TM involvement.　Results　(1) Middle colic vessels coursed between the two layers of the TM, and its' TM region attached to the posterior layer of the TM. (2) Mesenteric mass, increased mesenteric density, mesenteric vessels involvement and the enlarged lymph nodes in the transverse colon appeared in patients suffered from pancreatic carcinomas. The incidence of mesenteric masses was always concerned with the size of the pancreatic mass (p<0.01). (3) Pancreatic carcinomas usually invaded the root, body and margin of the TM. The tumor spread along the subperitoneal space and the anterior layer of the TM, and furthermore invaded into the small mesentery.　Conclusions　Specific CT images and anatomic features appeared once the TM involved by pancreatic carcinoma. CT is valuable for evaluating of TM involvement by pancreatic carcinoma.