Forage available to and used by the Alaskan moose, Alces alces gigas, during the winter of 1988-1989 on the Kenai Peninsula (Alaska, USA) was evaluated to test the hypothesis that changes in the quality and abundance of browse during winter affected selection of diet. Random plots were located in 3 age classes of vegetation (7-10, 20-30 and 70-80 years since the last fire), which varied in abundance and quality of browse. Dominant species of browse studied on those seral stands included scouler willow (Salix scouleriana [S. scoulerana]), kenai birch (Betula papyrifera kenaica [B. kenaica]), aspen (Populus tremuloides), and black cottonwood (Populus trichocarpa). Twig counts of current annual growth in early (December), mid- (February), and late (April) winter were made to determine amounts of woody browse available to and used by moose. Overall, moose browsed scouler willow, Kenai birch, and aspen in proportion to their availability, and avoided black cottonwood. Plant secondary compounds offer a likely explanation for moose avoiding cottonwood and not consuming white spruce (Picea glauca). Percentage use of a browse species, however, was not significantly related to its availability or to those measures of nutrient content analysed. Black cottonwood was not browsed to a greater degree in stands with low resource availability, contrary to a prediction of optimal foraging theory. Patterns of diet selection did not vary between periods of winter even though abundance of forage did so. Distance from escape cover affected diet selection by moose; selectivity of diet declined with increasing distance from cover, indicating that risk of predation played a role in the foraging dynamics of moose. The use of fire holds the potential to improve habitat for moose, but the population dynamics of this large herbivore also need to be considered for such management to be effective. Likewise, the sound management of moose requires that suitable habitat be available in other seasons as well as winter.