The four main types of appendiceal neoplasms are carcinoid tumors (CT), mucinous cystadenocarcinomas, colonic adenocarcinomas (CAC), and adenocarcinoid tumors. They have different clinical features and require different therapy. They are rarely diagnosed before or during surgery and frequently require a secondary operation for proper treatment. A series of 14 patients treated between 1979 and 1989 at Harris Methodist Fort Worth Hospital are described. There are six important points of management. (1) A frozen section should be done whenever the appendiceal findings are atypical. Then a diagnosis of malignancy can be made during surgery and appropriate surgery can be done primarily. (2) All patients with appendiceal neoplasms should be followed because a second malignancy will develop in 15% to 20% of them. (3) Appendectomy is recommended for patients whose CT are less than or equal to 1.0 cm in diameter and for most patients whose tumors are between 1.0 and 2.0 cm in diameter. Right hemicolectomy is preferred for those patients whose CT are 2.0 cm or more in diameter or between 1.0 and 2.0 cm with heavy lymphatic and mesenteric invasion. (4) Mucinous cystadenocarcinomas are slowly progressive and are best treated by means of right hemicolectomy with aggressive debulking added if pseudomyxoma peritonei is present. (5) CAC require a right hemicolectomy and have the same prognosis as have other colon adenocarcinomas. (6) Adenocarcinoid tumors have a dual cell origin, a predilection for developing ovarian metastases, and a malignant potential between CT and CAC. They are best treated by means of right hemicolectomy with concomitant oophorectomy in postmenopausal women.