Knowledge of the normal movements of whole lumbar spine and lumbosacral joint is important for evaluating clinical pathologic conditions that may potentially produce unstable situations in these regions. At present there are few studies that report systemic three-dimensional movement analysis of these regions. The purpose of this in vitro study was to quantitatively determine three-dimensional movements of the whole lumbar spine and lumbosacral joint. Ten fresh human cadaveric spine specimens including from L1 to sacrum (six specimens) and ilium (four specimens) were studied. Pure moments of a maximum of 10 N-m were applied incrementally. Parameters of neutral zone, elastic zone, and range of motion for rotations as well as for translations were measured. Neutral zones for flexion-extension, right/left axial torque, and right-left lateral bending were, respectively: 1.6 degrees, 0.9 degrees, and 1.4 degrees (L1-2); 1.0 degrees, 0.8 degrees, and 2.0 degrees (L2-3); 1.4 degrees, 0.7 degrees, and 1.4 degrees (L3-4); 1.8 degrees, 0.4 degrees, and 1.6 degrees (L4-5); 3.0 degrees, 0.4 degrees, and 1.8 degrees (L5-S1). Ranges of motion for flexion, extension, axial torque (one side), and lateral bending (one side) were, respectively: 5.8 degrees, 4.3 degrees, 2.3 degrees, and 4.9 degrees (L1-2); 6.5 degrees, 4.3 degrees, 2.6 degrees, and 7.0 degrees (L2-3); 7.5 degrees, 3.7 degrees, 2.6 degrees, and 5.7 degrees (L3-4); 8.9 degrees, 5.8 degrees, 2.2 degrees, and 5.7 degrees (L4-5); 10.0 degrees, 7.8 degrees, 1.4 degrees, and 5.5 degrees (L5-S1). Neutral zone values were small except for flexion at L5-S1.(ABSTRACT TRUNCATED AT 250 WORDS)