Introduction: Stretching is a therapeutic technique and may be used as a form of warm-up to increase flexibility or decrease pain throughout the movement, with objective to improve performance and reduce the risk of injury. Objective: To verify the acute and chronic effects of a program of static stretching compared with the dynamic one in performance of young soccer athletes. Methods: Randomized clinical study of equivalence carried out between August and November, 2010 with the under-17 category of the Grêmio Torrense club. After fulfilling the inclusion criteria, the athletes were randomly allocated into two groups: static stretching or dynamic stretching. All of them underwent an initial evaluation and were submitted to the first intervention. They were evaluated once again and at the end of 12 training sessions as well. Flexibility, impulse, speed, strength and muscle recruitment valences were evaluated. Results: The long jump has significantly improved in the two study groups; however, this improvement persisted in the chronic phase only in the static stretching group (p = 0.02). Flexibility increased significantly in both groups in the acute phase, but it only occurred in the static group following this improvement in the chronic phase (p = 0.03). The two examples of stretching led to decrease in performance in the velocity test. No improvement was observed in the hamstrings muscle strength throughout the study period in the two groups. Electric activity of hamstrings significantly decreased in the acute phase for the static stretching group (p = 0.035), while it significantly increased in the chronic phase in the dynamic stretching group (p = 0.038). Conclusion: It could be concluded that static stretching improves flexibility and long jump, while dynamic stretching improves muscular activation.