Wilms tumor, the most common pediatric urologic malignancy, and genitourinary rhabdomyosarcoma, the most common soft tissue sarcoma of childhood, represent two of the most commonly diagnosed pediatric urologic malignancies. The introduction and use of multimodal therapy (surgery, radiation, and chemotherapy) by the National Wilms Tumor Study (NWTS) and the Intergroup Rhabdomyosarcoma Study (IRS) groups have greatly improved the survival among children with these malignancies. Present survival rates for Wilms tumor exceed 85% and for rhabdomyosarcoma survival rates are approaching 80% as well. For Wilms tumor, current treatment trends suggest less intense therapy for those children with favorable histology tumors who are considered at relatively low risk for tumor recurrence. Likewise, the significant morbidity associated with the present therapy regimens for rhabdomyosarcomas has prompted investigators to search for individualized management schemes for children with a high probability of responding. The need for accurate criteria to separate these high and low risk groups becomes imperative. In this review we present our work using nuclear morphometry, as a prognostic indicator, to retrospectively predict response to therapy for children with Wilms tumors and genitourinary rhabdomyosarcomas.