The place of endoscopic ultrasound (EUS) is fundamental in neuroendocrine tumors of the gastrointestinal (GI) tract, and indeed EUS is themost performed examination for the diagnosis of location of these tumors. All the data of the literature shows that the EUS is superior to the other conventional techniques as the percutaneous echography, the helical scanner, and the magnetic resonance imaging (MRI). Besides, the development of the EUSguided fine-needle aspiration (FNA) allows to confirm by cytology the diagnosis carried out by EUS imaging. It is advisable to differentiate the well-differentiated neuroendocrine tumor (NET), where the indication of the EUS is done in front of an endocrine syndrome (hypoglycemia, hypergastrinemia, diarrhea), from the undifferentiated and non secretant pancreatic NET, where the indication of the EUS ismade in front of a pancreatic mass or more often in front of prevalent liver metastasis without primary lesion.