Functional disability after a Colles' fracture was correlated to the degree of axial shortening of the radius measured at the site of distal radioulnar joint. According to the sum of demerit points, the functional end result was unsatisfactory (fair or poor) in 4% of the patients with an acceptable anatomic result, in 25% of the patients with grade 1 shortening (corresponding to a shortening of 3 to 5 mm), and in 31% of the patients with grade 2 shortening (shortening of more than 5 mm). The results suggest that even a minor axial shortening of the radius, without concomitant malalignment of the articular surface, carries an increased risk of permanent disability.