The purposes of this study were to evaluate the ghrelin and leptin levels in a group of patients diagnosed with gastroenteropancreatic neuroendocrine tumors (GEP-NETs) and bronchopulmonary neuroendocrine tumors (BP-NETs) and to analyze the relationship between the body mass index (BMI), cachexia and selected NET markers. Here, LEP is linked to digestive system neuroendocrine tumor, grade 1/2.