Carcinoma of the colon in a 39-year-old woman which caused obstruction and inflammation of the appendiceal lumen remained undetected until postappendectomy complications prompted reevaluation and appropriate surgical intervention. Malignant lesions of the colon, especially the right side, are occurring with increasing frequency in young persons, and delay in recognition and definitive treatment is responsible for poor survival. A high index of suspicion in patients with atypical presentation of appendicitis or unusual operative findings should provide an opportunity for early diagnosis of underlying carcinoma.