Objective To analyze radiographic characteristics of pneumomediastinum in neonates,and to improve its diagnostic quality. Methods Supine anteroposterior chest film was taken in 22 neonates with pneumomediastinum, additional supine lateral chest film with horizontal projection simultaneously carried out in 16. One or more radiographic follow-ups was made in 14 cases. Spiral CT scanning was done in 4 patients. The imaging findings were retrospectively analyzed.Results Of the total 22 cases, thymic spinnaker-sail sign was seen in 9,transparent area cross the intermediate line of mediastinum in 9,streak and cystic transparent area scattered in the mediastinum in 4. Pneumothorax was accompanied in 12 cases.Conclusion Pneumomediastinum in newborn has its own radiographic characteristics. In most patients occurred thymic spinnaker-sail sign,or transparent area cross the intermediate line of mediastinum and frequently with pneumothorax. It is best shown by integrating supine anterioposterior films with lateral films of horizontal projection. CT scanning can provide more valuable information.