A porous hydroxyapatite tracheal prosthesis was implanted in rabbits after resection of a 15 mm circular segment of the cervical trachea. Postoperatively the animals were followed by radiography, bronchoscopy, and microscopy at the time of autopsy. The longest survival time was 22 weeks. All the rabbits died of infection at the prosthetic site or of progressive stenosis at the anastomoses. The prosthesis was incorporated by surrounding tissues, but no overgrowth of ciliated epithelium on the luminal surface of the prosthesis was observed. Although a hydroxyapatite tracheal prosthesis is tolerated in rabbits, covering of the luminal surface of the prosthesis with a non-porous layer to prevent infection and to permit mucosal overgrowth is necessary to achieve better long-term results.