Wet chemistry in organic solvents has proven highly efficient for the preparation of several types of metallic, metal-oxide, and semiconductor nanostructures. This Short Review focuses on the use of oleylamine (OAm) as a versatile reagent for the synthesis of various nanoparticle systems. We describe the ability of OAm to act as a surfactant, solvent, and reducing agent, as a function of other synthesis parameters. We also discuss the specific role of OAm either alone or in combination with other reactants, to form nanostructures using a variety of organic or inorganic compounds as precursors. In certain cases OAm can form complex compounds with the metal ions of the corresponding precursor, leading to metastable compounds that can act as secondary precursors and thus be decomposed in a controlled way to yield nanoparticles. We also point out that OAm-stabilized particles can often be dispersed in different organic solvents yielding solutions with enhanced colloidal stability over long times and the poten...