The authors reviews 11 new cases of adenocarcinoma of the appendix and 253 other cases described in the literature. The site of origin was imprecise in 2 of 3 cancers because it was total, abscessed or perforated. It was located proximally (45%) distally (37%) and in the midpoint (17.5%). Histologically it was orthoplastic or colloid mucosal dysplasic: stage I, purely mucous (17.5%); stage II, extraserous parietal (36.6%); stage III, regional (29%), or stage IV, metastatic (16 %). If a diagnosis is made during the course of an appendectomy by the finding of a small mass, rigid appendix, ileocecal ganglia or by the results of frozen section examination, immediate right hemicolectomy is necessary. Because diagnosis is often made by the pathologist, histologic examination should probably be performed on all appendices removed. Secondary right hemicolectomy must be performed, except for pure grade I, mucous cases and grade IV with widespread metastases. In grade III there was a 20% 5-year survival following appendectomy, 45 % following right hemicolectomy. In grade II there was a 70% 5-year survival following appendectomy versus 90% following right hemicolectomy.