Transitional cell carcinoma (TCC) of the bladder or renal pelvis is rare in children. We report 2 children with TCC of the bladder and 1 with TCC of the renal pelvis. One of the two children with bladder carcinoma experienced frequent intravesical recurrences, which is in contrast to the usual clinical course of bladder carcinoma in children. In the 3rd child, renal pelvic carcinoma was found incidentally in a renal pelvis specimen removed during pyeloplasty.