Year-to-year, geographical, and local variations in foliar concentrations of crude fat, nitrogen, total sugars, and starch and in foliar caloric value were determined for maturing, current-year needles of balsam fir (Abiesbalsamea L.). All except geographical variations proved to be statistically significant. Seasonal trends of chemical concentrations in maturing needles were in agreement with previous findings.Much of the variation in foliar caloric value could be explained by changes in foliar concentration of crude fat.Year-to-year changes in foliar nutrients may influence spruce budworm population dynamics.