Human invariant natural killer T cells (iNKT cells) are a unique population of T cells that express a semi‐invariantly rearranged T cell receptor (TCR) and are involved in a variety of immunoregulatory processes. We assessed the frequency of peripheral blood iNKT cells in 64 healthy Caucasian children from 7 months to 18 years of age and five cord blood samples by flow cytometry. iNKT cells were measured as CD3+ cells co‐expressing TCRVα24 and TCRVβ11 and using the monoclonal antibody 6B11, which recognizes specifically their invariant TCR rearrangement. The absolute number of iNKT cells ranged from 86 to 10,499 (CD3+/TCRVα24+/ TCRVβ11+) and 233 to 11,167 (CD3+/6B11+) iNKT cells per millilitre of blood. This range is stable from birth to adulthood. The relative iNKT cell count was found to be 0.003–0.71% (CD3+/TCRVα24/TCRVβ11) and 0.019–0.776% (CD3/6B11) of peripheral blood T cells and shows only a slight increase with age.