This study is based on a review of 204 cases of carcinoid tumors diagnosed at Memorial Hospital for Cancer and Allied Diseases during a period of 20 years (1950–1969). The carcinoids were divided into two major groups, deeply invasive and superficially invasive, based on their primary presentation; metastatic and nonmetastatic, according to follow-up information. When the primary tumor was invasive 85 per cent of the tumors metastasized and 65 per cent of the patients died of disease. On the other hand, less than one per cent of the superficially invasive carcinoids metastasized or caused death of the patient. Patients who had welldocumented hepatic and osseous metastases, significandy elevated urinary 5-HIAA, and carcinoid syndrome did not survive longer than one year, on the average.