Somatostatin is a peptide isolated originally from the hypothalamus and considered as an inhibitor of growth hormone secretion. However, further studies have shown that the peptide was ubiquitously distributed and exerts a large spectrum of physiological effects, mostly of an inhibitory nature. The very short half-life of the native peptide limits its therapeutic application. To overcome this limitation the long-lasting modified molecules (analogs) of somatostatin were synthesized. The present book provides comprehensive data on the application of somatostatin analogs in diagnostics and treatment of diseases, mostly endocrine disorders and cancers.