Ceftriaxone (cfx), a third-generation cephalosporin antibiotic, leads to transient cholelithiasis in some children, also known as pseudolithiasis. However, the underlying pathogenetic mechanism of this adverse effect has not yet been elucidated. We describe 3 children with ceftriaxone-induced pseudolithiasis, who were also carriers of the A(TA)(7)TAA polymorphism of the UGT1A1 gene, implying that a cause and effect relation may exist.