We report on 3 new cases of C trigonocephaly syndrome. In addition to the findings characteristic of this condition, one of the patients also had a large omphalocele. This patient was referred from a suburban hospital with a diagnosis of Down syndrome, stressing the fact that C syndrome is still under-recognized and underdiagnosed. Another patient was diagnosed at birth and immediately submitted to craniosynostectomy. A second operation was performed 7 months later resulting in normal brain growth and close to normal psychomotor development at 3 years, in contrast to the third patient, who was not treated surgically and was severely retarded at 4 years.