A patient had recurrent pyogenic infections, chronic mucocutaneous candidiasis, and repeated long-bone fractures. Her disorder was diagnosed as hyper-IgE syndrome on the basis of clinical data, elevated levels of serum IgE, increased levels of IgE specific for Staphylococcus aureus, and impaired T-lymphocyte function. Roentgenograms confirmed the diagnosis of osteogenesis imperfecta tarda. The estimated likelihood of both conditions occurring in the same person is approximately one in 10 billion. The coincident finding of bone dysplasia in a patient with impaired T-lymphocyte function suggests a common mechanism for birth defects.