A 50-year-old man was admitted with a diagnosis of acute appendicitis on January, 5, 1984 and an appendectomy was performed on the same day. The acutely inflamed appendix measured 7 cm in length, and a gross tumor, was seen at the apex. Histologic examination of the gross tumor, which was 1.7 cm in diameter, revealed a neoplasm representing a goblet cell carcinoid. Silver impregnation by both the Grimelius and Masson-Fontana methods disclosed a positive reaction in some neoplastic cells. Electron microscopically, endocrine granules with both limiting membranes and ahlos, 100-210 nm in diameter, were present in the neoplastic cells, Because of the relatively large size of the tumor and neoplastic invasion to the mesoappedix in this case and, in addition, the possible malignant nature of carcinoid tumor, ileoascendocolectomy was performed as an additional operation.