The scratch collapse test (SCT) is a relatively new clinical test in which a positive result implies entrapment neuropathy of the nerve tested. Initially described for carpal and cubital tunnel syndromes, subsequent authors have found it useful for the assessment of median, ulna, radial, axillary, and common peroneal nerves. We report a case illustrating the value of the SCT in the clinical assessment of thoracic nerve entrapment.