Introduction: The authors report a case of three brothers. Case descriptions: Two of these siblings presented with congenital growth hormone deficiency (GHD) and Chiari I malformation (CIM). The third younger brother has been found not to have GHD or the CIM. Discussion: Sparse cases of these two clinical occurrences have been reported. Further, the posterior cranial fossa (PF) has been determined to be altered in patients with CIM and GHD. Conclusion: Our current case reports strengthen the association between these two pathological entities and, to our knowledge, is the first description of both defects in siblings. © Springer-Verlag 2007.