The Authors underline the most important pathological, clinical and therapeutic aspects of appendiceal adenocarcinoid. Appendiceal adenocarcinoid is quite a rare tumor, presently considered as a single entity; it differs from typical carcinoid of the appendix because of its well definite histology, its aggressive behaviour and its poorer prognosis. There are no precise prognostic and therapeutic criteria to direct the operative choice between appendectomy and hemicolectomy. In particular the tumor diameter is of no use since the tumor often present diffuse rather than nodular growth. According to most Authors appendectomy is not sufficient in the following cases: liver lymph-node or retroperitoneal metastases; cecal meso-appendiceal or peritoneal spreading; histological poorly differentiated tumors, with nuclear atypia and high mitotic count. Some Authors performed hemicolectomy and bilateral oophorectomy in all case with peritoneal involvement since the ovaries are a frequent site of metastases.