A compact portable membrane inlet mass spectrometer (MIMS) has been used for the first time to detect and monitor, both qualitatively and quantitatively, volatile chlorinated hydrocarbons in the gaseous phase. Continuous monitoring of such compounds in the field is of importance due to their wide industrial use and their potential negative impact on public health and the environment. Compounds tested include vinyl chloride, 1,1-dichloroethylene, trichloroethylene and tetrachloroethylene. Gas phase experiments were performed at concentration levels from low ppb to low ppm. The results obtained showed very good linearity within the examined concentration range, ppb limits of detection and fast response (rise and fall) times. Mixture effects are also presented. The MIMS system was also investigated under periodic and dynamic experimental conditions and demonstrated stable and repeatable measurements.