Background and Purpose. The sit-and-reach test (SRT) is commonly used to assess flexibility of the spine and length of the hamstring muscles. The purposes of this study were (1) to describe hamstring muscle length as reflected by use of the SRT and the hip joint angle (HJA) in children, (2) to examine the correlation between SRT and HJA measurements, and (3) to examine gender differences for both measures. Subjects. The participants were 410 school-aged children (211 girls, 199 boys). Methods. Each child performed the SRT. In the final position, the SRT score was obtained and the HJA was measured using an inclinometer placed over the sacrum. Results. A mean SRT value of 24 cm and a mean HJA value of 81 degrees were obtained for all subjects. There was a strong correlation between the SRT and HJA measurements (r=.76). There was a difference between boys and girls for both measures. Conclusion and Discussion. The results suggest differences in expectations for hamstring muscle length in boys and girls. Although scores for the SRT and HJA were correlated, we prefer to assess hamstring muscle length using HJA scores because these scores are not influenced by anthropometric factors or spinal mobility. The results of this study suggest that HJA measurements guide treatment more effectively than do SRT measurements.