Myeloid and plasmacytoid dendritic cells (MDC/PDC) play crucial roles in bridging adaptive and innate immunity by affecting development of both cellular and humoral immunity. The immune system evolves after birth as reflected in dynamic changes in numbers and functions of various immune cells with age. However, age-associated changes in DC subsets in children have not been elucidated despite the fact that such normative data are crucial for evaluating alternations of DC subsets in various pediatric diseases. This study addressed age-associated changes in DC subsets and CD40/86 expression on PDC (markers of maturation/activation) in 50 healthy children in comparison with 25 children with specific polysaccharide antibody deficiency (SPAD). Our results revealed age-dependent decrease of PDC numbers (p < 0.0001), although there was no age-associated changes in CD40/CD86 expression. MDC1/MDC2 numbers did not reveal such linear age-dependent changes and MDC1/PDC ratio reached around 2 as typically seen in young adults after 10 years of age. In contrast, SPAD patients did not reveal such age-associated changes and showed decreased fluorescence intensity of CD86 in PDC cells. These results indicate lineage specific, age-dependent changes in DC subsets in normal children and possible altered development of these cells in SPAD children, emphasizing the importance of age-appropriate controls.