Abstract: Objective: Hoover’s sign – weakness of voluntary hip extension with normal involuntary hip extension during contralateral hip flexion against resistance – is a commonly used sign in the diagnosis of functional weakness of the lower limb. However, little is known about the performance of this sign in clinical practice.Methods: Hoover’s sign was tested as part of the diagnostic work-up of 337 patients presenting to hospital with suspected stroke. We made a gold-standard diagnosis of stroke, functional disorder, or other diagnosis based on clinical history and examination, imaging and clinical follow-up. We calculated the sensitivity, specificity, positive and negative predictive values of Hoover’s sign for a diagnosis of functional weakness in patients who presented with leg weakness.Results: We consecutively recruited 337 consecutive patients with suspected stroke, 124 of whom presented with leg weakness. 8 of these patients had a diagnosis of functional disorder. The sensitivity of Hoover’s sign for a diagnosis of functional weakness in those who presented with leg weakness was 63% (95% CI: 24 to 91), and the specificity was 100% (95% CI: 97 to 100).Conclusions: In this cohort, Hoover’s sign was moderately sensitive and very specific for a diagnosis of functional weakness. Further studies are required to assess inter-observer variability and performance of the test in larger numbers of patients with functional weakness.