In the previous studies, it is reported that traction diminishes the compressive load on intervertebral discs, reduces herniation, stretches lumbar spinal muscle and ligaments, decreases muscle spasm, and widens intervertébral foramina. The aim of this study was to evaluate the effects of horizontal motorized static traction on spinal anatomic structures (herniated area, spinal canal area, intervertebral disc heights, neural foraminal diameter, and m.psoas diameter) by quantitative measures in patients with lumbar disc herniation (LDH). At the same time the effect of traction in different localizations (median and poster olateral herniation) and at different levels (L4-L5 and L5-S1) was assessed. Thirty two patients with acute LDH participated in the study. A special traction system was used to apply horizontally-motorized static lumbar traction. Before and during traction a CT- scan was made to observe the changes in the area of spinal canal and herniated disc material, in the width of neural foramina, intervertebral disc heights, and in the thickness of psoas muscle. During traction, the area of protruded disc area, and the thickness of psoas muscle decreased 24.5% (p = 0.0001), and 5.7% (p = 0.0001), respectively. The area of the spinal canal and the width of the neural foramen increased 21.6% (p = 0.0001) and 26.7% (p = 0.0001), respectively. The anterior intervertebral disc height remained unchanged with traction however the posterior intervertebral disc height was significantly expanded. This study is the first to evaluated in detail and quantitatively the effect of motorized horizontal lumbar spinal traction on spinal structures and herniated area. According to detailed measures it was concluded that during traction of individuals with acute LDH there was a reduction of the size of the herniation, increased space within the spinal canal, widening of the neural foramina, and decreased thickness of the psoas muscle.