Electron capture gas chromatography techniques were used to obtain measurements of methyl chloride (CH3Cl) concentrations in the atmosphere, at latitudes ranging from about 65¿N to 90¿S. Most of the measurements were made over the Pacific Ocean. Average global concentrations within the boundary layer were found to be 815¿25 pptv in 1977 and 755¿37 pptv in 1978. Lower concentrations were observed above the boundary layer with average values of 629¿23 pptv and 618¿23 pptv in 1977 and 1978, respectively, within ¿20¿ of the equator, the boundary layer concentrations were significantly higher than those above the boundary layer. The sources, the sinks, the budgets, and the latitudinal distributions of CH3Cl are discussed in the paper.