Thirteen patients suffering from primary hypogammaglobulinaemia receiving intravenous immunoglobulin replacement therapy underwent computerized tomography of the paranasal sinuses. The CT scans were evaluated and related to clinical data from the patients, who were selected for study on the basis of having symptoms of rhinosinusitis. The scans varied from normal to demonstrating widespread sinus abnormality. There was no relationship between the scan findings and duration of ENT symptoms, range of current symptoms, or the interval between the onset of ENT symptoms and the start of intravenous immunoglobulin replacement therapy. It is nevertheless possible that prompt institution of replacement therapy, after correct diagnosis early in the course of the disease, may prevent the development of sinus disease refractory to such treatment.