We describe an oblique step-cut osteotomy technique for ulnar shortening. The technique requires no special instrumentation. It requires only an eight-hole 3.5-mm low-contact dynamic compression plate for fixation. Sixteen patients with posttraumatic ulnar impaction syndrome were treated. The average patient age was 40 years. The mean followup duration was 8 (range, 3 to 28) months. No nonunions occurred. Two patients required hardware removal for symptomatic hardware. Fourteen of the 16 patients reported persistence of occasional pain with some activities, but only 10 had any pain elicited at the time of examination. One patient required revision of the ulnar shortening procedure for persistence of symptoms. Functional outcomes were comparable with ulnar shortening performed by other methods. However, this technique might offer improved union rates compared with those described in the literature and is applicable to treat ulnar impaction syndrome arising from other causes.