Between May 1995 and June 1999 we equipped 81 barren-ground grizzly bears (Ursus arctos) with satellite radio-collars within a study area of 235,000 km(2), centred 400 km northeast of Yellowknife, Northwest Territories. We estimated 71 annual ranges of radio-tracked animals (greater than or equal to 38 locations years) using the 95% fixed kernel technique with least squares cross-validation. Annual ranges of males ((x) over bar= 7,245 km(2), SE = 1,158, n = 26) were larger than ranges of females ((x) over bar = 2,100 km(2), SE = 279, n = 45). Ranges increased in size as the proportional amount of exposed bedrock and other marginal habitats in the environment increased. Annual ranges are the largest reported for grizzly bears in North America.