Organochlorine chemicals, including chlorinated pesticides and polychlorobiphenyls, are found at appreciable concentrations in the polar regions, presumably as a result of long-range atmospheric transport. Concentration data in arctic and antarctic air, snow, atmospheric deposition, fish and seals, measured by various investigators, are compiled and interpreted to determine latitudinal and temporal trends. It is suggested that the often surprisingly high concentrations are explained in part by the temperature-dependent partitioning of these low volatility compounds. A process of global fractionation may be occurring in which organic compounds become latitudinally fractionated, "condensing" at different ambient temperatures dependent on their volatility. We suggest that compounds with vapor pressures in a certain low range may preferentially accumulate in polar regions. Possible adverse effects of these potentially toxic compounds on the indigenous population and on the arctic ecosystem are discussed. It is concluded that there is a need to control or even ban certain chemicals which have a tendency to fractionate into the polar ecosystems.