Applications of mass spectrometry to high polymers has been traditionally handicapped by an inability to volatilize the sample without decomposition and a lack of mass range in available mass spectrometers. Thus gaseous ion sources were confined to studies of pyrolyzed polymers in which polymer identity and structures were inferred from detailed mass spectrometric analysis of their volatile products. This branch of mass spectrometry is still vitally active and is being advanced to new levels of sophistication and utility using advanced computer-based pattern recognition and artificial intelligence strategies. The direct analysis of polymers started mainly as series of largely unrelated observations on systems with oligomers of extraordinary volatility and stability, most commonly fluoro polymers. These studies demonstrated the validity of the mass spectrometric approach but these techniques were only exploited effectively after developments in methods for conversion of solid samples into gaseous ions. Of these methods of ionization, field desorption played a major role and now has an established place in studies of synthetic polymers. Developments of sputter ionization methods, particularly PD–MS and FAB–MS, demonstrated the ability to successfully ionize materials with molecular weights measured in tens of thousands. Development of these ion sources has stimulated the production of mass analyzers designed to match their proven mass ranges. While mass spectrometry is still only operating at the lower end of the traditional high polymer molecular weight range, it has nevertheless come of age as a technique for studying high molecular weight materials. While its range of applicability now overlaps with many well-established techniques such as GPC, osmometry, viscometry, light scattering, etc. it is clear that mass spectrometry offers potential advantages.