Mesenteric cyst is one of the rarest tumours, with about 820 cases reported since 1507. Ultrasound and TC are the most valuable modalities for diagnosis of mesenteric cyst. Surgical resection is the treatment of choice. The authors report two cases of mesenteric cyst of the transverse mesocolon preoperatively diagnosed by ultrasonography and computed tomography (CT). A surgical enucleation was performed.