This study was undertaken to investigate the viscoelastic properties of the human thoracolumbar spine. Uniaxial tensile failure tests were performed on two groups of specimens obtained from 18 individuals 40-85 years old. These groups of specimens were selected as related to anatomical fiber orientation, i. e. caudomedially and caudolaterally.The biomechanical properties of the specimens were determined at five different strain rates of 0. 1, 0. 25, 1.3, and 4 sec-1. The maximum stress, strain at rupture, and Young modulus were obtained for each group. The results show that there is no significant difference between both anatomical orientations for all the biomechanical parameters.However, the maximum stress, strain at rupture and Young modulus were found to increase with increasing strain rates(up to 3 sec-1). At higher levels, the strain at rupture and the modulus become constants suggesting an upper limit.