Abstract: Objective: Measure the lumbosacral angle in intervertebral disc herniation and analyse its significance in the diagnosis of this disease. Methods: The radiograms of 102 cases with intervertebral disc herniation were observed and their lumbosacral angles were measured using Grogkopff's technique to compare with normal controls Results: Apart from the direct X-ray characteristics described in former literatures, the lumbosacral angle of L ₅S ₁ intervertebral disc herniation was significantly greater than that of L _4~5 intervertebral disc herniation and normal people （P ＜0.01）. However, there was no significant difference between the latter two groups （P ＞0.05）. The possible reasons were: （1）The appearance of intervertebral pressure imbalance; （2）The compensatory effect for relaxing nerve root compression; （3）The result of imbalance of flexion and extension strength of the spine. Conclusion: Measurement of the lumbosacral angle may help in the diagnosis of L ₅S ₁ intervertebral disc herniation.