Introduction and objectives: Decreased hamstring muscle length is frequent in athletes. To measure hamstring muscle length, valid and specific tests are required. The aim of this study was to determine the validity of the sit-and-reach and toe-touch tests as measures of hamstring muscle length in young paddlers. Methods: Sixty-four young paddlers (mean age: 13.35 ± 0.59 years) performed the straight leg raise test (in both legs), the sit-and-reach and the toe-touch tests in a random order. For the straight leg raise, the angle of the straight leg to the horizontal was measured. For the sit-and-reach and toe-touch tests, the maximal distance reached was measured. Results: Correlation values between sit-and-reach and toe-touch scores with respect to the straight leg raise were moderate in both boys (r = 0.66-0.77) and girls (r = 0.74-0.85). In comparison with the normal reference range, boys showed a greater frequency of decreased hamstring muscle length in the straight leg raise (63.6%) than in the sit-and-reach and toe-touch tests (25.0%-34.0%). No differences were found in girls. Conclusions: The validity of sit-and-reach and toe-touch scores for measuring hamstring muscle length is moderate, although girls showed higher values than boys. However, when sit-and-reach or toe-touch scores were used to measure hamstring muscle length in young canoeists, we found a greater number of false negative results in boys.