In recent decades, isolation of the peptides secreted by gastrointestinal neuroendocrine tumors has greatly advanced our understanding of the pathophysiology of the syndromes resulting from over-production of these biologically active compounds. Early detection of these lesions permits localization and surgical extirpation prior to the development of mestastatic disease. In 1995, early detection of gastrointestinal neuroendocrine tumors hinges on an appropriate index of suspicion on the part of the primary care physician. The prompt recognition of the typical clinical constellations of symptoms associated with these tumors is essential to their timely diagnosis and management.