The presenting features of 39 patients with mucopolysaccharidosis (MPS) type IH are described. The mean age at diagnosis was approximately 9 months and it is difficult to see how this can be reduced without consideration of newborn screening. An earlier age at diagnosis is likely to lead to better results following therapy such as bone marrow transplantation. Clinical features which should arouse suspicion of MPS IH include frequent ENT surgery and recurrent herniae. Clinical vigilance is needed for early diagnosis.