The indications for surgical correction of craniosynostosis in which there is involvement of only one of the cranial vault sutures have traditionally been based upon the cosmetic merits of the deformity alone. Whilst it is now appreciated that intracranial hypertension is commonly associated with the more complex forms of craniosynostosis, this aspect has not previously been addressed in detail among cases of single-suture craniosynostosis. This retrospective study reports our experience of overnight subdural intracranial pressure monitoring in 74 children with premature closure of a single cranial suture. A single coronal suture was involved in 37 patients, the sagittal suture in 25 and the metopic suture in 12. Intracranial pressure was raised in 13 (17%), borderline in 28 (38%) and normal in 33 (45%). Elevated intracranial pressure was seen more commonly where a midline suture was involved (sagittal or metopic) than when a single coronal suture was fused. We conclude that intracranial hypertension occurs in a significant proportion of children with single-suture craniosynostosis and suggest that this factor should be borne in mind during the initial assessment of these children so as to enable timely intervention where required and appropriate counselling of parents.