In 1991 and 1992, changes were made to the rate structure and eligibility requirements of the Northern Air Stage Program. To determine the effect of these changes on the affordability of a nutritious diet, food price surveys were conducted in 20 isolated communities, staging points, and selected southern cities and used to cost a 46-item Northern Nutritious Food Basket (NFB), which meets the nutrient requirements of a reference family of four. Food affordability was calculated as the percentage of "after-shelter" social assistance income required to purchase the NFB. In the Northwest Territories (NWT), from 100% to 123% of income was required in Air Stage communities in 1990-1991 and from 86% to 125% in 1993. In the provinces, from 65% to 83% of income was needed in 1990-1991 and from 56% to 98% in 1993. In Kangiqsujuaq and Nain, the amount of "after-shelter" income needed increased by as much as 6% and 15%, respectively. Changes to the Northern Air Stage Program reduced the cost of perishable foods and improved the affordability of a nutritious diet in the NWT. Affordability is also affected by social assistance income. In most isolated communities, families would still find it difficult to afford a nutritious diet.