Vertical profiles of aerosol characteristics obtained near Svalbard, Norway, during the Arctic Gas and Aerosol Sampling Program (AGASP) indicate that high aerosol concentrations and strong visible haze were distributed throughout the troposphere. Layers of Arctic haze were observed in both dry air and moist air. A research flight on March 31, 1983, crossed a previously undocumented Arctic aerosol front structure. Condensation nucleus concentrations of 450 cm-3 within the polluted continental air mass south of the front decreased to 80 cm-3 within the clean Arctic air north of the front. Aerosols above the Aitken size range decreased one order of magnitude in both number and mass across this same air mass boundary.