Fuel weight is a major factor influencing the intensity of forest fires. Moisture content, fineness, compactness, and continuity of fuel, as well as prevailing weather conditions, also influence fire intensity since they affect both the amount of fuel available for combustion and the rate of burning. Behavior of fires results from the complex interaction of these factors. Fuel weight, however, is one of the most important considerations in describing fuel hazard since it determines potential fuel energy release and remains reasonably constant over time. Weight of tree crowns, the subiect of this paper, is a particularly important component of forest fuels during crown fires or slash fires. Previous studies have shown that crown weight of many conifer species can be predicted from bole dimeter and crown length of individual trees (Kittredge 1944; Storey et al. 1955; Fahnestock 1960; Wendel 1960; and Brown 1963 ). The trend of increasing crown weight with increasing bole diameter is similar for some species but varies considerably among others because of physical differences in foliage and habit of branching. Very little previous research adequately identifies the variation in crown weight due to site quality and stand density. This paper describes for red pine (Pinus resinosa Ait. ) and jack pine (Pinus banksiana Lamb.) the relationship between weight of individual crowns and different conditions of site quality and stand density. It also presents a simple method for estimating the crown weights of these species. This method is applicable for estimating both overstory fuel in uncut stands and the amount of slash created by thinning or harvest cutting.