Many authors have described percutaneous pinning techniques as the treatment of choice for most supracondylar fractures. But little information is available concerning ulnar nerve injury resulting from pinning techniques. When the surgeon is faced with a postoperative ulnar nerve palsy, it can be the result of unrecognized preoperative palsy, manipulation during surgery, or damage to the nerve by one of the medial pin placements. The options for management include exploration, medial pin removal, or observation. We reviewed our hospital records on the 132 supracondylar elbow fractures that we treated in children from 1991 to 1998 There were 16 palsies found with normal preoperative and abnormal postoperative ulnar nerve function. Normal nerve function returned without exploration and early medial pin removal in all cases. We recommand that observation is the appropriate way to manage these postoperative ulnar nerve palsies in most cases.