Neuroendocrine tumours (NETs) are heterogeneous neoplasm, arising from different endocrine cells distributed in many organs and tissues which share a common neuroendocrine phenotype. The neuroendocrine cells of the human body are confined to certain organs such as thyroid, pancreas or adrenals, or are dispersed throughout the body in the respiratory tract and abundantly in the intestinal mucosa. These cells belong to the diffuse endocrine cell system, which is the largest endocrine system in the body. They are able to accumulate precursor molecules in small synaptic vesicles or large dense core granules, which are then processed into hormones, peptides or amines. The hormones and amines are then released on stimulation either to the blood stream or to adjacent cells or neurons, and the release is tightly controlled. The released peptides and amines regulate various processes in the human body, such as gastrointestinal secretion, blood pressure, response to stress and regulation of local and global homeostasis in the skin. NETs present a wide spectrum of malignant diseases from rather benign to very malignant and lethal variants. They are classified according to differentiation status and tumour cell type. NETs may occur in any organ, but are mainly detected in the gastroenteropancreatic (GEP) system and in the lungs. A general and common classification has involved considerable work by the best pathologists in the world. Our current knowledge about NETs tumour biology and treatments has changed dramatically during the last decade. The main problems that clinicians and translational scientists face in overcoming these malignancies relate to various topics within molecular pathogenesis of neuroendrine tumours. My speech will hopefully highlight the importance of tumour biology, signaling transduction, genomics and biomarkers discovery in developing potential new therapeutic and diagnostic approaches to improve clinical management of NET patients.