Resumo. The willow (Salix x rubens) is a woody plant of European origin, used in Brazil for handicrafts and furniture. This culture is eventually attacked by caterpillars and ants, which cause the loss of the leaf area. This study aimed to evaluate the effect of levels of defoliation on the growth of willow. The experiment was conducted in a greenhouse. The plants were kept in pots with a capacity of 8 liters under intermittent mist, from August to December 2004. The design was a randomized block with five replications and four treatments (0, 25, 50 and 75% defoliation of the total number of leaves) were evaluated for reducing sugar content, leaf area and fresh and dry stems and leaves. The defoliation reduced the final weight (WR = -0,1067x + 19,03, R² = 0,98) and diameter of the rods (DM = -0,0114x + 5,172, R² = 0,98), and the leaf weight (MF = -0,1028x + 13,892; R2 = 0,99) and leaf number (NF = -0,2545x + 36,87, R² ~ 0,998). The partition of assimilates has been modified in favor of the restoration of leaf area.