Immunological studies in mice and humans have demonstrated that glutaraldehyde-processed, irradiated bovine cartilage elicits a nearly undetectable immune response, even on second-set provocative implantation in humans. Previous clinical studies have shown that this material performs in a manner comparable to irradiated allograft cartilage as an implant material for facial contour restoration. We used implants of bovine cartilage processed by irradiation and glutaraldehyde cross-linking for nasal reconstruction in 53 patients. In 50 of these cases, the implants remain in place, without observable changes in size or shape, after periods ranging from one to seven years. Two implants were lost to apparent absorption within fifteen months. A third implant was palpably in place after five years but was undetectable two years later. Ten of the surviving implants have been in place for three years or longer, and 4 over five years. In most cases, implants of processed, irradiated bovine cartilage appear to be firmly encapsulated, dimensionally stable, and immunologically inert after periods in situ during which more primitive bovine cartilage implants consistently have been absorbed. Our results are confirmed by x-ray examination and enzyme-linked immunosorbent assay.