Recurrent abdominal pains (RAPs) represent a common problem in children sometimes leading to unnecessary and invasive procedures. The rates of appendectomy were evaluated consecutively in 180 children with idiopathic hypercalciuria (HC) and/or hyperuricosuria (HU) and RAPs, and in 270 control subjects. Of the HC/HU patients 10% and of controls 1.5% underwent appendectomy (p<0.0001). In 15 out of 18 HC/HU patients appendectomized, RAPs persisted with the same frequency and severity after the operation; 10 out of 18 had dysuria and/or gross hematuria 2 days-12 months after appendectomy. At our first visit, urinalysis was negative for hematuria in 13 out of 18 patients and in eight out of the 10 with a previous history of dysuria or gross hematuria. Pain recurrences resolved or improved in nine out of the 11 patients followed at least 1 year after general or specific therapy for HC/HU. The inconstant association of dysuria and hematuria with RAPs in children with HC/HU may lead to the urological origin of pain being overlooked, and may explain the high rate of appendectomy among these children. The possibility of HC/HU therefore should be taken into account in children with RAPs even when dysuria and hematuria are not present.