Background/aim: The serum immunoglobulin levels are used routinely in clinical practice because they provide key information the humoral immune status. This study aimed to determine the age-related reference values of serum immunoglobulin levels in healtchildren. Materials and methods: A total of 330 healthy children, aged between 0 and 18 years, were included in this study. The serum immunoglobulin levels were measured using a nephelometric method in a total of 11 groups, each group consisting of 30 individuals, and IgG subclasses in 6 groups of children aged more than 2 years. Results: The serum IgG levels were high during the newborn period, decreased until the sixth month, and again increased to a maximum level at the age of 18 years. The level of IgA was found to be extremely low in the newborn period and then increased with age. While the lowest value was in the newborn period for serum IgM level, the highest value was in the 16-to 18-year-old period. The IgG subclasses varied depending on the age groups. Conclusion: The updated reference intervals of immunoglobulin levels in children may be used for the accurate diagnosis of immudeficiencies.