We report on a 6-year-old girl with C-trigonocephaly syndrome and diaphragmatic hernia. She is severely mentally retarded and shows the characteristic findings of this syndrome, including trigonocephaly, unusual facial features, especially intra-oral anomalies, low set and dysplastic ears, cardiac anomaly and neonatal hypotonia. Following our presentation at the 5th European meeting of dysmorphology in Strasbourg, P. Meinecke brought to our attention a case of C-trigonocephaly who died in the neonatal period from complications of a diaphragmatic hernia. Another case of C-trigonocephaly without diaphragmatic hernia was communicated to us by D. Lacombe. We report these three observations and present a review of 26 alleged cases.