The hyper-IgE syndromes are rare, complex primary immunodeficiencies characterized by clinical manifestation diversity, by particular susceptibility to staphylococcal and mycotic infections as well as by a heterogeneous genetic origin. Two distinct entities--the classical hyper-IgE syndrome which is inherited in an autosomal dominant pattern and the autosomal recessive hyper-IgE syndrome--have been recognized. The autosomal dominant hyper-IgE syndrome is associated with a cluster of facial, dental, skeletal, and connective tissue abnormalities which are not observable in the recessive type. In the majority of affected patients with autosomal dominant hyper-IgE syndrome a mutation in the signal transducer and the activator of the transcription 3 gene has been identified, leading to an impaired Th17 cells differentiation and to a downregulation of an antimicrobial response. A mutation in the dedicator of the cytokinesis 8 gene has been identified as the cause of many cases with autosomal recessive hyper-IgE syndrome and, in one patient, a mutation in tyrosine kinase 2 gene has been demonstrated. In this paper, the authors provide a review of the clinical manifestations in the hyper-IgE syndromes with particular emphasis on the diversity of their phenotypic expression and present current diagnostic guidelines for these diseases.