Sural nerve grafts were used in three patients to bridge gaps measuring 2 1/2 to 4 1/2 cm in previously transected but not repaired posterior interosseous nerves. The grafts were done at 4, 5, and 7 months after injury. Extension was weaker in all three than on the uninjured side, but the range of motion was complete, with the exception of a slight lag of index finger extension and partial return of extension of the extensor carpi ulnaris in the same patient. All three patients recovered full function of the involved hand 1 year after grafting. The properties of the posterior interosseous nerve (pure motor and short distance to the muscle) contribute to good results with nerve grafts in delayed nerve repairs. We believe that these results are better than tendon transfers, at least in young patients.