Background: Mechanical origin low back pain (MLBP) is the leading cause of work disability and the largest generator of direct and indirect care costs of any health system. There is no medical test to diagnose MLBP, although a test was designed in 2004 for the clinical diagnosis of MLBP. Materials and methods: A prospective cohort study was conducted on 183 patients with nonradicular back pain and had a positive Hamstring Biped Extension Test (HBET) from 2004 to 2014. All (100%) of the patients included in the cohort were rehabilitated using the McKenzie protocol until the pain disappeared, or the patients were unable to improve their rehabilitation process. Additionally, the presence of related anatomical pain generating factors was assessed using various diagnostic imaging tests (MRI, scintigraphy, etc.).Results: All patients had a positive HBET when they were included in the cohort. All had diagnostic imaging performed. The pain measured on a visual analogue scale (VAS) had a mean of 7.7 (range 2-10/10). There was a mean follow-up time of 2.24 months (range 1-6 months), with a mean of 20.94 (range 10-60) physiotherapy sessions. A negative result was obtained for the HBET in 100% of patients (P = .05). There was a mean improvement of 0.84 (range 0-3/10, P = .05) on the VAS pain measurement at discharge.Discussion: The HBET is a useful clinical test for the diagnosis of MLBP, with a positive predictive value of 100%. Low back pain was not associated with diagnostic image tests findings in our cohort in the presence of a positive HBET.Evidence level: II.