Both forearms of 36 patients who had been treated with an anterior locking plate using the trans-flexor carpi radialis approach for unilateral distal radial fractures were investigated by ultrasonography from the distal end of the radius to 5 cm proximally before plate removal. After fixation of the anterior locking plate, the median nerve was significantly more radially located to the flexor carpi radialis tendon than on the healthy side and showed hypertrophy and flattening at the distal end of the radius. In six cases, the median nerve on the plate side lay radial to the flexor carpi radialis tendon. The median nerve after plate fixation may lie more radially than its original position. Confirming the radial deviation of the median nerve by ultrasonography before removal of the anterior locking plate is useful to prevent the complication of median nerve injury. Level of evidence: IV