Introduction Immunoglobulin represents the main therapy for patients with inborn errors of immunity (IEI) and it is a safe procedure, but adverse events (AEs) can occur with variable frequencies. Objective To evaluate the frequency of immediate AEs to intravenous immunoglobulin (IVIG) regular therapy in a pediatric cohort with IEI after a pre-IVIG infusion protocol. Methods This was a longitudinal study from 2011 to 2019 at a tertiary pediatric hospital in Brazil. Results A total of 1736 infusions were studied in 70 patients with IEI, 46 (65.7%) of whom were males and whose median age was 5.8 years old (range: 6 mo - 18 yo). Seven different brands of IVIG were used with the median loading dose of 0.57g/kg (range: 0.23 - 0.88g/Kg). According to the protocol, pre-medication and step-up infusion rate, were performed in 1305 (75.2%) infusions. Immediate AEs were noted in 10 children (14.3%) and in 22 (1.2%) infusions. Skin reactions (rash or urticaria) were the most common AE with 14 episodes (0.8% of all infusions). Almost all AEs were mild (19/86.4%), with no severe ones being observed. The majority of the AEs (81.8%) was identified at a 0.04ml/kg/min infusion rate. Gender, age at first infusion, presence of infection on the infusion day and change of the IVIG brand were evaluated and none of them were associated with AEs. Conclusion The low frequency of immediate AEs in children with IEI highlights the safety and tolerability of intravenous immunoglobulin replacement with the procedures established at our center.