The stages in the closure of the growth plate after percutaneous epiphyseodesis were studied in fourteen patients (eight girls and six boys) with coronal T1-weighted spin-echo images and coronal field-echo images of the knee. A total of thirty-three magnetic-resonance imaging studies of the knee were made the first week, the fourth month, the eighth month, or one year after the epiphyseodesis. A mature bridge of bone was seen at the operative sites approximately eight months after the operation. In the central undisturbed area between the operative sites, there was a progressive decrease in the width of the physeal cartilage that remained visible eight months after the operation. Growth recovery lines were not seen postoperatively in any patient, and the physis closed in all of the patients. The physis of the adjacent untreated bone served as a control bone and showed neither a change in width nor any growth recovery lines. Magnetic resonance-imaging studies provide excellent visualization of the anatomical changes that lead to closure of the physis after an epiphyseodesis, and we believe that these studies provide a method of assessment of the physis after an injury.