The authors describe 20 cases of carpal tunnel syndrome (cts), caused by repetitive microtrauma at work. The clinical and electromyographic data are compared with a control group (406 pt affected by non traumatic cts). In the control group, the syndrome appeared more frequently in the right side (mostly in men), in relation to the manual dominance. These data suggest that the importance of "physiological traumatism" is decisive in the pathogenesis of the syndrome. Patients affected by microtraumatic stc show a better EN-Graphic pattern versus the control group, likely imputable to a earlier diagnosis.