We evaluated the diagnostic sensitivity of quantitative sensory testing (QST), using the CASE IV system, in 14 patients with clinically diagnosed small-fiber neuropathy and normal traditional electrodiagnostic studies. All patients had at least 1 abnormal threshold, 13 patients had abnormal heat-pain thresholds, 8 had abnormal cold thresholds, and 7 had abnormal vibration thresholds. QST is therefore highly effective in documenting dysfunction in small fiber neuropathy patients.