A model was developed to estimate total leaf dry weight of individual standing trees ofEucalyptusregnansF. Muell. in even-aged, monoculture stands aged 8–20 years. Tree biomass data were collected for a sample of 42 trees from four plots at three sites in Victoria and Tasmania. One plot had been heavily thinned 10 years prior to sampling. The model was based on the pipe model theory,L(x) = as(x)p(x), whereL(x) is leaf dry weight above some height (x),s(x) andp(x) are, respectively, stem sapwood area and permeability atx, and a is a parameter. Permeability is known to vary with site and tree conditions, and an empirical model was developed that replacedap(x) in the pipe model theory with a function in terms of tree age, diameter at breast height over bark, and distance along the stem from the tip of the tree. The resulting model to predict leaf weight appeared to be unbiased across sites, among trees within sites, and with respect to thinning treatment. It was found that given a prediction from the model of total leaf dry weight of one tree, it could be assumed with 95% confidence that the true value of leaf weight fell within an interval bounded by values of −60 to +76% of the estimate. When the model was used to predict stand leaf weight by summing estimates from many individual trees, the interval was bounded by minimum values of −3 to +19% of the stand estimate. These errors of estimate were probably conservative. It appeared that errors of similar magnitude may apply to other published models of this type.