There remains no standard PSLR procedure, no consensus on interpretation of results, and little recognition that a negative PSLR test outcome may be of greater diagnostic value than a positive one. The causal link between LBP pathology and hamstring action remains unclear. There is a need for research into the clinical use of the PSLR; its intra- and interobserver reliability; the influences of age, gender, diurnal variation, and psychosocial factors; and its predictive value in lumbar intervertebral disc surgery.