Typhlitis is a necrotizing inflammatory disease of the cecum, usually with secondary infection. It is most often found in acute leukemia patients on chemotherapy but has also been reported in other patients on chemotherapeutic drugs. Diagnostic features of typhlitis have been reported on plain radiographs, barium enema, angiography, CT, and one other reported case with ultrasound. We report three cases of typhlitis with a characteristic echogenic thickening of the mucosa on ultrasound. The sonographic findings in the one previous report were identical to those of our three cases. We believe that the sonographic findings of typhlitis are unique and that ultrasound offers an easy noninvasive method of diagnosing this potentially lethal disease.