The paper reports on two cases of pneumomediastinum in the newborn child: a benign form with clinical picture and radiological scan of subcutaneous cervical emphysema; and a severe form of pneumocystosis complicated with suffocating pneumomediastinum and pneumothorax. The authors discuss the etiopathogenic aspects of pneumomediastinum in the newborn, the clinical and radiological semeiologies, the latter being of a high diagnosis importance. The therapeutic modalities are indicated in terms of the extent to which breathing is affected.