Total nonstructural carbohydrate (TNC) concentration, an estimate of the carbohydrate energy readily available to the plant, was measured by chemical extraction (enzymatic hydrolysis) in dormant season roots of sugar maple (Acer saccharum Marsh.). In all sample trees, TNC concentration increased as root diameter decreased. On the average, root diameter explained 60% of the variation in TNC concentration within an individual tree. Linear regressions of TNC concentration on root diameter did not differ significantly among trees. Bias on TNC concentration introduced by differences in root size can be minimized by sampling similar root diameter classes among trees, or by adjusting TNC concentration to a common root size. For. Sci. 37(1):343-346.