The "necktie lasso" is a new technique that allows the simultaneous active treatment, of both Wartenberg's sign and claw deformity of the fifth and the fourth digits in the hand with ulnar nerve palsy. The flexor sublimis of the fourth digit is taken by a palmar approach. It is then divided into two strips up to the proximal part of the palm; The radial strip is used as a classical "direct lasso" to treat the claw deformity of the fourth digit; The ulnar strip is wound around the base of the fifth digit by a palmar and dorsal approaches at the level of the proximal phalanx, like a necktie, being medial to its radial pedicle, dorsal and superficial to its extensor apparatus, then lateral to its ulnar pedicle; It is then recovered in the palm and sutured to itself. From September 1998 to April 2003, this technique has been used in eight patients aged between 21 and 35 years old and suffering from post traumatic low ulnar nerve palsy. It was always very effective in dealing with Wartenberg's sign: the active adduction of the fifth digit appearing at the start of flexion. The claw deformity of the fourth and fifth digits was equally actively corrected. No complications are reported in this series. With a mean follow-up of 3 years there was no recurrence of any of the deformities.