OBJECTIVE To determine the extent to which the clinical manifestations of a cohort of people undergoing surgery for lumbosacral nerve root compression satisfy those described in The National Institute for Health and Care Excellence (NICE) guidance. METHODS We studied consecutive admissions for lumbar nerve root decompression surgery at two neurosurgical units. Pre-operatively, each person's clinical manifestations were documented and compared with NICE's description. Post-operatively, at three time points (within 48 h, 3 months, 12 months), each person rated their symptoms as either better, the same, or worse. RESULTS Pre-operatively, one person (0.8%), from 123 admissions, under 20 different consultant neurosurgeons, had manifestations consistent with NICE's clinical description of lumbar nerve root compression. Post-operatively, self-reported benefit associated with surgery appeared high, at all three time points (78-91%), supporting the diagnosis of symptomatic nerve root compression and the value of surgery. CONCLUSIONS In this small sample, from two units, NICE's description of the clinical manifestations of lumbar nerve root compression did not describe 99% of people having surgery for it. Using NICE's definition to triage people with low back pain could result in prolonged symptoms and delayed treatment. Diagnosing lumbar nerve root compression is complex. NICE's guidance requires examination.