Thirty five patients affected by primary immunodeficiency diseases were treated with a polyethylenglicol treated intravenous gammaglobulin. Number of infusions administered during a period of 665 months/patients, was 110. In those cases previously treated with intramuscular gammaglobulin, serum IgG levels were higher after intravenous gammaglobulin administration. Therapeutic response was favourable in most cases. Intravenous gammaglobulin was well tolerated, noticing only two serious and two mild adverse reactions. Patients that suffered adverse reactions with intramuscular gammaglobulin tolerated well intravenous preparation used, except for one patient that after two years in treatment developed IgE mediated antibodies against IgA. Need of an individualized dosage is emphasized.