Intravenous immunoglobulin (IVIG) is commonly used in primary and secondary immunodeficiency diseases as well as autoimmune conditions as immunomodulatator treatment. Immediate adverse events which are generally mild and occur during infusion are seen in 6 hours. Reported immediate adverse events are in a wide range from 1%-40% in pediatric patients. 115 patients who received IVIG (except newborns) were included into this crosssectional study. IVIG was given to patients for primary immunodeficiencies (n=8), ITP (n=65), Kawasaki disease (n=11), secondary immunosupression (n=28), and passive immunization (n=3). 5%, 10% IVIG preparations and pentaglobin were used. Headache, fever, chills, nausea, rash, arthralgia, myalgia and back pain were accepted as mild immediate events. There were 62 (54%) boys and 53 (46%) girls aged 1 month-18 years. Mean age of the group was 7.4 +/- 4.6 years. Immediate adverse events due to IVIG infusions were seen in 29 (25.2%) of all patients. Gender and types of the disease were not different in significance regarding the presence of adverse events. The rate of adverse events did not change with receiving pre-medication. The most common reaction was fever/chills. Immediate reactions were seen in first 6 hours in 7 patients and during infusion in the remaining. They were treated with slowing of the infusion rate and infusion was stopped in 3 patients because of moderate events. Because of the increasingly use of IVIG therapy, it is important to know the side effects. High doses, high infusion rates, accompanying infection may worsen the adverse effects especially in primary immunodeficiency diseases.