Asphyxiating thoracic dysplasia (Jeune syndrome) is an osteochondrodysplasia with autosomal recessive inheritance, characterised by a nanism with rhizomelic predominance, associated with a narrow thorax. It induces an alteration of the respiratory function that conditions the prognosis, which is worsened in case of associated visceral lesions (probably related to mutations of genes implicated in ciliary development, as recently described). We report the observation of two severe cases of Jeune syndrome to emphasize the advancement of imaging, especially echography, and molecular biology in establishing prenatal diagnosis as well as prognosis of this syndrome.