A study of 221 claw fingers of fifty-one leprosy patients with ulnar or combined ulnar and median-nerve paralysis showed that the severity of the deformity was determined mostly by the completeness of paralysis of intrinsci muscles, and to a lesser extent by the duration of paralysis. There was no predilection for severe deformity in any one finger. Recurrent dislocation of the extensor tendon from the knuckle of the metacarpophalangeal joint was observed mostly in fingers that were completely deprived of all intrinsic muscles. No satisfactory explanation could be found for this. Flexing the wrist facilitated opening of the claw finger, but the effect was more evident at the metacarphophalangeal joint than at the proximal interphalangeal joint.