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Aerial surveys to assess polar bear (Ursus maritimus) productivity were conducted along the northern coast of Ontario during February and March, 1974 through 1978. Cub production varied from 33 to 112 annually, and averaged 71 during the 5-year period. Average litter size was 2.0. Emergence extended from late February to early April with the peak around 1-15 March. Maternity dens occurred throughout the northern coast; distances inland extended from 29 to 118 km. The section between the Winisk and Severn Rivers consistently contained the greatest concentration of family groups. Most dens were situated in open or treed bog habitat where snow accumulation was greatest. Maternity dens lacked the presence of an earth chamber or intricate internal structures recorded in areas further north. After emergence, family groups remained in the den vicinity for 2 to 3 weeks. Movement to the sea was usually quite direct, and invariably towards Hudson Bay, although James Bay was sometimes much closer. Some groups travelled over 300 km to reach seal (Phoca hispida) hunting areas on the Hudson Bay ice. Maternity denning on Akimiski Island represents the most southerly occurrence of reproducing polar bears currently known anywhere in the world.