Gastroenteropancreatic neuroendocrine tumors (GEP-NETs) are rare and heterogeneous neoplasms that can arise from neuroendocrine cells throughout the body. These tumors are classified into well-differentiated neuroendocrine tumors (NETs) and poorly differentiated neuroendocrine carcinomas (NECs) based on the WHO criteria established in 2010. Functional tumors produce peptides and hormones, causing symptoms like diarrhea, hypoglycemia, and gastrointestinal ulcers, while non-functional tumors lack characteristic symptoms and are clinically evident due to mass effects such as jaundice and abdominal pain. The incidence of GEP-NETs is rising, with an annual rate of about 1.3–3.5/100,000, peaking in the late 50s. The most common site is the small intestine, followed by the appendix and the pancreas. Prognosis is determined by the presence of distant metastases and the proliferative activity/grading of the tumor. Diagnosis of GEP-NETs involves a multidisciplinary approach, with complete tumor resection being the only chance of cure. Cross-sectional imaging using CT or MRI is crucial for initial staging, particularly in detecting locoregional or distant metastases. PET/CT scans targeting somatostatin receptors are highly sensitive for GEP-NETs, facilitating therapeutic options for G1/G2 tumors. However, poorly differentiated NECs often lose somatostatin receptor expression, making 18fluorodeoxyglucose PET/CT the preferred diagnostic tool.Gastroenteropancreatic neuroendocrine tumors (GEP-NETs) are rare and heterogeneous neoplasms that can arise from neuroendocrine cells throughout the body. These tumors are classified into well-differentiated neuroendocrine tumors (NETs) and poorly differentiated neuroendocrine carcinomas (NECs) based on the WHO criteria established in 2010. Functional tumors produce peptides and hormones, causing symptoms like diarrhea, hypoglycemia, and gastrointestinal ulcers, while non-functional tumors lack characteristic symptoms and are clinically evident due to mass effects such as jaundice and abdominal pain. The incidence of GEP-NETs is rising, with an annual rate of about 1.3–3.5/100,000, peaking in the late 50s. The most common site is the small intestine, followed by the appendix and the pancreas. Prognosis is determined by the presence of distant metastases and the proliferative activity/grading of the tumor. Diagnosis of GEP-NETs involves a multidisciplinary approach, with complete tumor resection being the only chance of cure. Cross-sectional imaging using CT or MRI is crucial for initial staging, particularly in detecting locoregional or distant metastases. PET/CT scans targeting somatostatin receptors are highly sensitive for GEP-NETs, facilitating therapeutic options for G1/G2 tumors. However, poorly differentiated NECs often lose somatostatin receptor expression, making 18fluorodeoxyglucose PET/CT the preferred diagnostic tool.