The mass balance and long-term variability of the perennial sea ice in the Arctic Ocean are of interest as indicators of the state of the Arctic sea-ice pack. The area of ice cover during summer has long been recognized to have a significant influence on the heat balance of the Arctic. In fact, various studies have focused on the possibility and consequences of decreases, or disappearance, of the summer ice pack. In contrast, in winter, the entire Arctic Ocean is covered with a compact ice cover and, therefore, variations in the maximum Northern Hemisphere sea-ice cover are determined primarily by conditions in the Bering, East Greenland, Barents, and other marginal seas. The primary factors determining the amount of multi-year ice, which is ice that survives the summer melt season, are the growth in thickness during winter, summer ablation, and ice export mainly through Fram Strait. In this paper, the total area of multi-year ice in the Arctic Ocean from 1979 through 1986 is determined using passive microwave imagery from the Nimbus-7 satellite. The variations in the total multi-year ice area in several regions are described and compared with calculations of the divergence of the ice pack using the University of Washington Arctic Ocean Buoy data. From 1979 to 1981, the total observed multi-year ice decreased about 15%, remained low through 1982 and 1983, and recovered to previous values during 1984 and 1985.