Leg and pelvic motion were studied during passive straight leg raising on twenty-three male subjects without low back pain. A sonic digitizer was used to measure angular displacements of the pelvis during right and left straight leg raising. Angles of rotation were calculated for total leg lift motion in the sagittal plane, and pelvic motion in both the sagittal and transverse planes. The mean angle of rotation for leg lift motion was 59.3° ±9.1 and 60.6° ±8.9 for right and left leg trials, respectively. Mean angle of pelvic rotation in the sagittal plane was 16.9° ±3.0 and 17.1° ±3.3 for right and left leg trials, respectively. The ratio of pelvic rotation in the sagittal plane to leg lift rotation was 3.522 ± 0.751 and 3.491 ± 0.671 for right and left leg trials, respectively. Mean angle of pelvic rotation in the transverse plane was 1.6° ±2.5 and -1.5° ±2.6, respectively, for right and left leg trials. Rotation of the pelvis in the transverse plane occurred toward the non-lifted leg.