The authors present the case of a child diagnosed as having Beckwith-Wiedemann syndrome and Chiari I malformation. Hemihypertrophy is associated with Beckwith-Wiedemann syndrome and has been described in conjunction with Chiari I malformation. The authors hypothesize that the hemihypertrophy that may involve the skull base and Chiari I malformation found in their patient are not spurious findings but are pathologically related, perhaps by slight dysmorphologies of the posterior cranial fossa.