Although median sternotomy is used for most cardiac procedures, postoperative dehiscence remains a serious and persistent problem. This investigation was designed to assess new bone formation and sternal healing across the linear osteotomy of the sternum and to determine if rigid fixation would enhance bony healing and thus decrease unfavorable sequelae. To test this hypothesis, 14 skeletally mature baboons (Papio anubis) underwent standard median sternotomy; seven sternotomies were closed with interrupted 24-gauge cerclage wires, and seven, with thin Vitallium compression miniplates and transverse lag screws. The sterna from each group were harvested en bloc at 4 and 8 weeks, radiographed, processed, and serially sectioned and stained for histomorphometry to assess the quantity of new bone across the linear osteotomy. Clinical stability was superior with the plated and lag screw group at 4 weeks; however, by 8 weeks, no clinical difference between treatments was apparent. Histomorphometric analysis indicated that the linear osteotomy gap treated with plates and screws was less than the gap associated with the wire group. Rigid fixation of the sternum resulted in earlier union with primary osseous healing, suggesting greater inherent stability. these factors may decrease adverse sequelae for this procedure.