The concentrations of carbon tetrachloride, tetrachloroethylene. 1,1,1-trichloroethane, and bromoform have been determined for Arctic seawater in the Svalbard area in August and September 1980 by a pentane extraction of the seawater followed by glass capillary gas chromatographic separation and electron capture detection. The vertical distributions in a transection across Fram Strait show an inflow of 50 tons/year of carbon tetrachloride, 46 tons/year of tetrachloroethylene, and 114 tons/year of 1,1,1-trichloroethane due to contamination of Atlantic water in the industrial latitudes, and the outflow through the same transection 50, 60, and 129 tons/year, respectively. The uncertainties in these figures are estimated to 50%. Bromoform has a biogenic source in the belts of benthic algae growing in the coastal waters of Svalbard. The mean concentrations for open surface waters were 0.83 (s = 0.17) ng/L, 0.68 (s = 0.23) ng/L, 2.5 (s = 1.8) ng/L, and 9.8 (s = 4.0) ng/L for carbon tetrachloride, tetrachloroethylene, 1,1,1-trichloroethane, and bromoform, respectively. The anthropogenic substances, carbon tetrachloride, tetrachloroethylene, and 1,1,1-trichloroethane, show an undersaturation in the surface water compared with atmospheric northern hemisphere concentrations, which is why the Arctic seawater is thought to act as a sink for atmospheric halocarbons from anthropogenic sources. The biogenic production of bromoform causes an oversaturation in open sea surface waters when compared with the atmospheric background, which is why bromoform is supposed to be a source of atmospheric bromine.