The automated electron capture gas chromatographic determination of the atmospheric concentrations of CCl4 are reported for the period July 1978 to June 1981 at five coastal monitoring stations. Adrigole (Ireland), Cape Meares (Oregon). Ragged Point (Barbados, West Indies), Point Matatula (American Samoa), and Cape Grim (Tasmania). Daily measurements at approximately 6-hourly intervals are always complimented by an equivalent number of on-site calibration measurements. Estimates of CCl4 emissions to the atmosphere from known industrial sources are compared with the measured trends and the absolute values of the observed concentrations. A globally averaged atmospheric lifetime for CCl4 is calculated by using an optimal estimation technique incorporating a nine-box model of the atmosphere. The average global concentration of CCl4 from July 1978 to June 1981 in the lower troposphere was 118 pptv, and it was increasing 2.1 pptv/year over this period. Both the absolute concentration observed and its trend are consistent with the calculated releases of CCl4 and its expected destruction by stratospheric photolysis.