Abstract: The direct on-line coupling between high performance liquid chromatography (HPLC) and proton nuclear magnetic resonance (NMR) spectroscopy is one of the most powerful techniques for simultaneous separation and structural elucidation of unknown compounds in mixtures.The resolution,detection limit and multiple solvent suppression of the 1H NMR spectra obtained in HPLC-NMR are described. Recent advances in the hyphenation between other separation methods and NMR spectroscopy are discussed.