The chlorine and bromine contents in tobacco and tobacco smoke in both the particulate and gaseous phases were studied by neutronactivation analysis. Methyl chloride and methyl bromide concentrations were measured in the gaseous phase by gas-liquid chromatography — mass spectrometry. The chlorine and bromine contents in nine brands of cigarettes were on the average as follows: Tobacco—6600 ppm chlorine and 110 ppm bromine. Cigarette smoke, particulate phase—68 μg chlorine and 1 μg bromine per cigarette. Cigarette smoke, gaseous phase—90 μg chlorine and 5 μg bromine per cigarette. In the gaseous phase methyl chloride accounted for 60% of the total chlorine and methyl bromine for 80% of the total bromine.