Objective To improve X-ray and clinical knowledge of asphyxiating thoracic dysplasia(ATD).Methods X-ray film and CT findings of twin infants were studied meanwhile relative literature about ATD was reviewed.Results The main positive fingings of ATD were as follow:(1)The thoracic cages were both shorter than usual in the transverse and anterioposterior diameter;the anterior ends of the ribs are widened and cupped;(2)The pelvis also show abnormalities which include some flaring of the ilia,and early ossification of the centers for the capital femoral epiphyses;(3)Incureable respiratory infection was the prominent clinical manifestation.Conclusion ATD,a rarely seen disease,often occurs in those patients who suffer from pneumonia repeatedly;Because plain films can clearly show the relative characteristic deformity changes of thoracic cage and pelvis,X-ray examination can be regarded as the most important diagnostic method.