We report the clinical evolution of three adult patients with recurrent respiratory tract infections. Those patients had a low plasma level of IgG3 and/or a deficiency in anti polysaccharide antibodies. They all were previously treated with intravenous immunoglobulin, but their clinical status as well as their health related quality of life improved after they had switched to subcutaneous immunoglobulin administrations. The frequency of subcutaneous injections was on a weekly basis and the dosage was adjusted in order to reach the cumulative monthly dose of intravenous infusions. The tolerance of the subcutaneous route of immunoglobulin injection was recorded as excellent in all three patients.