Lateral deviation of the upper beak (“scissor beak” or “wry beak”) is a common malocclusion in many species of birds but appears to be a common presentation in macaws (Ara species). This article describes transsinus pinning, a procedure in which a pin is passed through the frontal sinuses, turned parallel to the upper beak, and attached to the tip of the beak with an orthodontic rubber band to provide constant tension on the beak as it grows. The tension of the rubber band is maintained until the beak is considered straight. The results of 16 cases in which this beak-straightening procedure was used are presented. The age of the chicks that had their beaks straightened ranged from 7 to 28 weeks, and they were placed into 2 groups: those younger than 12 weeks (12 chicks; 75%) and those older (4 chicks; 25%). Complete resolution was achieved in 87.5% (14 of 16) of the avian patients that were treated with this procedure. The 2 remaining cases (12.5%) failed to fully respond. The 12 younger birds (75%; age, 7–12 weeks; median, 10 weeks; range, 5 weeks) responded to treatment within 2 weeks (12–85 days; median, 14 days; range, 73 days); the remaining 4 older chicks (25%; age, 14–28 weeks; median, 17.5 weeks; range, 14 weeks) required a longer period (13–90 days; median, 25.5 days; range, 77 days) for the beak to straighten. Transsinus pinning is a simple, effective, and rapid technique for correcting this malocclusion in macaw chicks younger than 16 weeks old. With this approach, in most cases, excellent results can be expected in only 2–4 weeks.