Clinical diagnosis of carpal tunnel syndrome usually is easy and sensitive, but frequently, it is based on history and referred symptoms when no motor or sensory deficits are observed during examination. In patients with carpal tunnel syndrome, a dissociation between the severity of the disease reported by the patient and the deficits clinically evaluated by the physician often are observed. The Italian Carpal Tunnel Syndrome Study Group did a multicenter study on 740 patients (1123 hands) with carpal tunnel syndrome to assess the aspects of dissociation between the patient's and the physician's quantification of the disease severity and the ability of the patients with carpal tunnel syndrome to do daily activities. Validated patient-oriented parameters assessing symptoms and hand functional status were used. The relationship between the physician's and the patient's measurements is strong with a linear significant correlation when analyzing the functional status of the hand but not so clear and simple when analyzing the symptoms. Patients with mild-to-moderate carpal tunnel syndrome seemed to function well, although severe symptoms may be reported by the patient; however, when nerve impairment becomes severe, the patient's hand function is extremely impaired although symptoms may be milder. The data show that the patient's point of view is reliable. Carpal tunnel syndrome seems to be an ideal model to evaluate the importance of patient-oriented measurements.