We evaluated IgG subclass levels in 11 symptomatic patients (ages between 3 and 22; mean 7.5 years) with IgA deficiency, seven with selective IgA deficiency, and four with low IgA levels. All patients had experienced three or more episodes of sinopulmonary infections a year. Combined IgG2-IgG4 deficiency was detected in two patients, IgG2 deficiency in one patient and IgG4 deficiency in two patients. Elevated IgG1 and IgG3 levels were detected in most of the IgG subclass deficient and sufficient patients. It is known that gammaglobulin replacement therapy reduces the frequency of infections significantly in IgG subclass deficiency. Although immunization against IgA is a risk in IgA deficiency, these patients can be treated with gammaglobulins containing low IgA.