Background/Purpose: Bilateral Wilms’tumors present a therapeutic challenge, p articularly with delay in presentation, when there is poor response to chemother apy and when associated with nephroblastomatosis. The primary aim of management is eradication of neoplasm, while at the same time preserving of renal function. Methods: Nineteen bilateral Wilms’tumors were seen in our service between 1981 and 2003. This represented 10%of the 190 patients with Wilms’tumors seen duri ng this period. There were 12 female and 7 male patients ranging in age from 7 m onths to 8 years. Fourteen had synchronous presentation, one of whom had liver m etastasis at diagnosis. Of the 5 patients with metachronous tumors, 3 had their initial nephrectomies done elsewhere. Nephroblastomatosis was identified in 18 ( 95%) of the patients. Treatment was, in most cases, according to National Wilms Tumor Study Group protocols, with initial bilateral biopsy, neoadjuvant chemoth erapy, and tumorectomy. Where indicated, nephrectomy (partial or complete) invol ved using ice dam topical cooling and vascular control, and in one case, bench s urgery and extensive renal reconstruction with orthotopic autotransplantation. R evision tumorectomy was used on 3 occasions for recurrence in areas of nephrobla stomatosis. There were 6 extrarenal relapses. Results: Ten patients are alive an d free of disease 1 to 15 years after treatment, all with well preserved renal f unction (lowest recorded glomerular filtration rate was 85 mL/min per 1.73 m2). Nine have died (2 of unrelated disease), including 6 of the 7 with spread outsid e the kidney. All 3 with unfavorable histology are alive. Of the 5 with metachro nous presentations, 4 are alive, as are 7 of 10 who presented in the last decade . Conclusions: Appropriate chemotherapy and conservative nephron-sparing and in novative surgery can achieve good results with preservation of adequate renal fu nction in nearly all cases. Nephroblastomatosis was an almost universal finding and requires close monitoring because Wilms’tumors developed in residual suspec t areas. Revision surgery was effective. Unfavorable histology did not have a re duced survival in our series. Metastatic spread outside the kidney had a poor pr ognosis. Background / Purpose: Bilateral Wilms’ tumors present a therapeutic challenge, p articularly with delay in presentation, when there is poor response to chemother apy and when associated with nephroblastomatosis. The primary aim of management is eradication of neoplasm, while at the same time preserving of renal function. Methods: Nineteen bilateral Wilms’ tumors were seen in our service between 1981 and 2003. This represented 10% of the 190 patients with Wilms’tumors seen in this period. There were 12 female and 7 male patients ranging in age Of the 5 patients with metachronous tumors, 3 had their initial nephrectomies done elsewhere. Nephroblastomatosis was identified in 18 (95%) of the patients. Treatment was, in most cases, according to National Wilms Tumor Study Group protocols, with initial bilateral biopsy, neoadjuvant chemothrapy, and tumorectomy. Where indicated, nephrectomy (partial or complete) invol ved using ice dam topical cooling and vascular control, and in one case, bench s urgery and extensive renal reconstruction with orthotopic autotransplantation. R evision tumorectomy was used on 3 occasions for recurrence in areas of nephrobla stomatosis. There were 6 extrarenal relapses. Results: Ten patients are alive an d of of disease 1 to 15 years after treatment, all with well preserved renal f unction (lowest recorded glomerular filtration rate was 85 mL / min per 1.73 m2). 2 of 3 with unfavorable histology are alive. Of the 5 with metachro nous presentations, 4 are alive, as are 7 of 10 who presented in the last decade. Conclusions: Appropriate chemotherapy and conservative nephron-sparing and in novative surgery can achieve good results with preservation of adequate renal fuction in nearly all cases. Nephroblastomatosis was an almost universal finding and requires close monitoring because Wilms’tumors developed in residual suspec t areas. Revision surgery was effective. Unfavorable histology did not have a re duced survival in our series. Metastatic spread outside the kidney had a poor pr ognosis.