In children with recurrent abdominal pain (RAP), the location of pain to the flank may suggest the involvement of the urinary apparatus. We aimed to evaluate the location of pain in different age groups of children with idiopathic hypercalciuria (HC) and/or hyperuricosuria (HU) and RAP. Location of pain was assessed in 180 consecutive HC/HU children with RAP, aged 3-17.6 y, presenting to a single centre. Considering four age groups, central/diffuse was more prevalent than lateral location of pain in youngsters, with a progressive and significant (p<0.0001, chi2 test for trend) decrease of the prevalence of central/diffuse location with rising age, and with the most relevant drop after age 8 y. Location of pain was central/diffuse in 81% of patients under and lateral in 79% of those over 8 y of age (p<0.0001). The location of pain changed from central/diffuse to lateral in 16/18 children followed at least 1 y, within 1 to 2 y by age 8. Only after 8 y of age did the lateral location of abdominal pain become the rule in children with HC/HU and RAP. This has to be kept in mind in order to avoid overlooking the urologic origin of pain.