Resumo. In this research experiments were accomplished with two classes of vegetable hormones (gibberellin and cytokinin); with the objective of verifying the effect of gibberellic acid and 6-Benzylaminopurine (GA 3 and BAP) on the lignification and the longitudinal growth in seedlings of Eucalyptus grandis . The experiment was accomplished greenhouse, where were the growth regulators combined or isolated applied, in the following concentrations: GA 3 (49.13 μM e 98.26 μM); BAP (111 μM e 222 μM), with five repetitions for each treatment. The comparisons among the averages of the height of the plants to the 6 months showed that the most pronounced prolongations of the stem corresponded to the treatments G [2] , G [2] C [1] and G [2] C [2] where the largest concentration of GA 3 was used. In the treatment G [1] C [1] where it was combined to smallest concentration of GA 3 with to smallest concentration of BAP (49,13 μ M de GA 3 + 111 μ M de BAP), it happened the smallest lignin tenor 23,37%.