A longitudinal study was performed of eight patients with fronto-nasal dysplasia. The follow-up exceeded 15 years in some patients. The eight cases showed lipoma of the corpus callosum. The only clinical alterations observed were cosmetic ones. No neurological abnormality was found, although their intellectual level was just within normal limits, the average IQ being 95, ranging from 82-103. No relationship between the IQ and the type of facies or the size of the lipoma was found. All the children presented psychological alterations, especially misanthropy and shyness. The lipoma was diagnosed by computerised tomography. Two otherwise unidentifiable small lipomas were found with this technique. Pneumoence-phalography and carotid arteriography, which had been performed on nearly all the patients before CT scanning, had demonstrated some alterations. These anomalies slightly deformed the anterior portion of the lateral ventricles and anterior cerebral arteries, but a lipoma in the corpus callosum had not been considered. Only in one case was hypogenesis of the corpus callosum clearly demonstrated. The presence of an extra-osseous lipoma on the forehead and of a vertical bony bar in the intracranial midline in contact with the frontal bone are definite signs of the presence of a lipoma in the corpus callosum. The lipoma is in anterior contact with the vertical bony bar. The neurological alterations presented by the patients in this series are minor compared with those described by other authors writing of children with lipoma of the corpus callosum without FND. Because of mild clinical alteration in these children we have not considered removing the lipoma.