It is necessary for orthodontists to collect and analyze the patients' photographic data. By conventional methods, these photo data were commonly saved on film, which were frail and often resulted in data loss. Furthermore, it is not convenient for the orthodontists to consult and study these data during clinical research. A critical problem thus arises in managing these photo data scientifically. The computer technique and picture processing method were employed in the present study to establish the Photo Management System for Orthodontics (PMSO), which makes the administration of patients' photo data more scientific, convenient, and effective than before. This system is characterized as follows: 1. Clinical orthodontists designed and programmed the system, which is "close to clinical reality and serves the clinic". Orthodontists can easily use it without any training course. 2. The images can be imported from many devices, such as digital cameras, scanners, and electronic data storage media such as floppy disks. 3. Even two groups of photos (four images) could be displayed in the same window for comparison and study. This function allows orthodontists to easily observe the differences in the same patient's photos at different stages, which is important to obtain comprehensive knowledge of the patient. 4. The network technique makes it possible for the photos to be shared. The orthodontists can get the patients' photos through the network without going to the radiology department or the imaging room. 5. It is helpful for orthodontic research since the photos can be exported easily in different ways. 6. This is shared software; orthodontists can use it for free. Schlagwörter: orthodontics, photo management, image processing, photo grouping, clinical application