The carbon economy of young walnut grafted trees in their second growing year, was investigated through carbohydrate analysis and 14C-labelling experiments. In October, 3 weeks before leaf-fall, starch and soluble sugars represented up to 25% of the total dry matter, with starch highly predominant among them. Sucrose was more abundant in the bark than in the wood, while the starch content was similar in both compartments. The reserves were located in the wood and in the innermost pith. Between October and January, the minor roots (ø < 15mm) underwent a significant depletion of their August-labelled reserves, whereas the tap-root was the main organ depleted between January and May (early growth resumption). Both labelling experiments, and root respiration monitoring, provided some information about the timing of translocation processes and the early metabolism of the translocation compounds.