A procedure is described for obtaining allometric regression equations to estimate non-destructively and in a cost-effective manner the current year's above-ground vegetative and reproductive biomass of Vitis vinifera L. Merlot' throughout the growing season. Significant relationships were obtained over a 3-year period (1998-2000) between the dimensions of an individual shoot per vine (i.e. diameter and length) and dry weights of its primary stem, primary leaves and lateral growth. The dry mass of a grape was best estimated from measurements of the basal diameter of the bunch peduncle. Introducing cumulative degree-days as an additional explanatory variable in the equations allowed them to be used irrespective of year and growth stage. Multi-year regressions were used to quantify in detail the seasonal evolution of mature grapevine biomass under the climatic conditions of the Bordeaux area, France, and for differing levels of soil nitrogen.