INTRODUCTION: The authors report a case of three brothers. Two of these siblings presented with congenital growth hormone deficiency and Chiari I malformation. The third and younger brother has been found not to have growth hormone deficiency or the Chiari I malformation. RESULTS: Sparse cases of these two clinical occurrences have been reported. Further, the posterior cranial fossa has been determined to be altered in patients with Chiari I malformation and growth hormone deficiency. CONCLUSION: Our current case reports strengthen the association between these two pathological entities and are, to our knowledge, the first description of both defects in siblings.