Carcinoid tumors are complex neuroendocrine malignancies affecting the gastrointestinal system and sometimes the respiratory and hepatobiliary systems. Presentation of symptoms depends on the origin of the carcinoid tumor. Carcinoid syndrome develops when carcinoid tumors metastasize to the liver and produce systemic symptoms from secretion of neuroactive hormones, particularly serotonin. Diagnosis involves imaging and a combination of endoscopy, biochemical testing, and PET-CT. The mainstay of treatment is with surgical resection of the primary tumor and potentially lymph nodes or metastatic disease if present. Unfortunately, opportunities to treat carcinoid tumors systemically are limited.