The mass spectrometer (MS), when used as a detector for the gas chromatography yields a system (GC/MS) which is compatible, sensitive, and provides specific information, suitable for qualitative or quantitative analyses for industrial hygiene samples. Examples of the use of two GC/MS/Data Systems utilizing industrial hygiene samples as encountered during the health hazard evaluation efforts of NIOSH (National Institute for Occupational Safety and Health) are presented. A quadrupole unit has been used as a service tool to analyze industrial field samples and a high resolution double focussing unit has been used in the areas of method development research.