In order to determine the nature of tissue repair after removal of condyles, bilateral condylectomies were performed in seven growing female Macaca fascicularis. Two animals underwent condylectomies only, and five animals were fitted with maxillary and mandibular splints before undergoing condylectomies. One condyle from each condylectomized animal was processed for histologic examination. Four animals, with intact condyles, were available as controls: Two had splints placed, while the other two did not undergo any treatment. Nine mo after surgery, the histology of 12 resection sites and 12 control condyles (seven removed at condylectomy and five at death) was compared. In the control condyles, hypertrophic cartilage was seen over the entire condylar surface. From the 12 resection sites, five showed hypertrophic cartilage, non-hypertrophic cartilage cells were present in three, and four demonstrated bone apposition and resorption. Cartilage was present only at the medial and central aspects of the surgical site, and in every specimen, bone was seen at the lateral pole. Two out of 12 fossae overlying surgical sites contained hypertrophic cartilage, while the five control glenoid fossae showed bone, an intermediate zone, and a fibrous capsule. Because of the variety in tissue response and the small number of animals in each group, the effect of the splints could not be determined. Based on the results of this study, the following was concluded: (1) Regeneration of organized hypertrophic cartilage with inherent growth potential can take place after condylectomy, albeit not in every instance and only in the medial aspect of the stump. In the lateral aspect, and also medially if hypertrophic cartilage does not reform, bone is predominant. The original height is not recovered. (2) The cartilage of the glenoid fossa is capable of adaptive changes similar to those seen in condylar cartilage.