Neuroendocrine Tumors (NETs) encompass a wide variety of tumors arising from neuroendocrine cells, which produce bioactive substances. The incidence of NETs increased significantly lately, becoming one of the most common tumors of the digestive tract. Their clinical presentation is as diverse as their capacity for hormone production. Carcinoid syndrome is the most common hormonal syndrome produced by NETs and is characterized by diarrhea, flushing and cardiac valvular lesions. New research brought multiple changes in the classification of these neoplasms and a new understanding about their diagnosis and treatment, promoting a multidisciplinary approach. Somatostatin analogues, radiation, biological, and cytotoxic drugs have improved the prognosis of these patients, which entails a great challenge for healthcare providers.