OBJECTIVES: The aim was to investigate age-dependent serum levels and occurrence of elevated celiac disease (CD)-related antibodies in young children, to define the optimal serological procedure when selecting for small intestinal biopsy. PATIENTS AND METHODS: Included were 428 children with biopsy verified CD (median age 16 months; range 7.5 months-14 years) and 216 controls (median age 2.7 years; range 8.5 months-14.6 years). Immunoglobulin (Ig) A antibodies against gliadin (AGA-IgA), tissue transglutaminase (tTG-IgA), and endomysium (EMA-IgA) were analysed. RESULTS: Increased serum AGA-IgA levels were found in 411 of 428 CD cases, tTG-IgA in 385 of 428, and EMA-IgA in 383 of 428. In the control group, 11 of 216 had increased levels of AGA-IgA, 5 of 216 of tTG-IgA, and 8 of 216 of EMA-IgA. In CD children younger than 18 months, elevated AGA-IgA occurred in 97% and elevated tTG-IgA and EMA-IgA were found in 83% of the cases. Conversely, in CD children older than 18 months, elevated AGA-IgA occurred in 94%, and elevated tTG-IgA and EMA-IgA were found in 99% of the cases. CONCLUSIONS: In children older than 18 months, both tTG-IgA and EMA-IgA are sufficiently accurate to be used as a single antibody marker, whereas a large proportion of younger children with CD lack these antibodies. Therefore, when selecting children for small intestinal biopsy, the detection of a combination of AGA-IgA and tTG-IgA is optimal for identifying untreated CD in children younger than 18 months.