We present an antenatal ultrasonographic diagnosis of the cerebro-costo-mandibular syndrome. This rare dysmorphic disorder (only 51 cases have been reported to date) mainly associates defective costal development with features of the Pierre-Robin syndrome. The diagnosis is very often made at birth and the prognosis is very poor. Antenatal ultrasound examination may show a combination of orofacial and chest maldevelopment. In our case the diagnosis was made at 20 weeks' gestation during a routine ultrasound examination and the patient chose to terminate the pregnancy at 24 weeks.