Malignant tumors of the appendix are rare and are histologically similar to those arising elsewhere in theintestines. The frequency of specific tumor types and the clinical presentation of symptomatic tumors are,however, significantly different. Before surgery, correct diagnosis of a malignant appendiceal tumor is rare; mosttumors are diagnosed by a pathologist while examining an appendectomy specimen. With the advent of high resolutionimaging modalities (ultrasound and helical CT), malignant tumors of the appendix may be more accurately diagnosed;this report describes the imaging findings of malignant appendiceal tumors.