Wilms' tumor occurs in 5-10 % of all cases of nephroblastoma. The metachronous form represents 2-3 % of cases. Most (96.2 %) metachronous tumors appear within the first 5 years of the primary tumor. Associated malformations are more common in bilateral cases. Metachronous tumors are a therapeutic challenge. We describe the case of an 11-year-old girl with left hemihypertrophy. The diagnosis was metachronous relapse of Wilms' tumor 7 years after the first diagnosis. The patient received five courses of preoperative chemotherapy and tumorectomy was performed. Because of post-surgical complications, nephrectomy was performed on her only kidney. Since she is anephric, the patient is in chronic renal failure and is dependent on dialysis. Treatment with carboplatin and etoposide was continued after surgery and the patient is currently in complete remission. The appearance of a metachronous Wilms' tumor 5 years after that of the primary tumor is rare. When a contralateral tumour develops, chemotherapy must be given until the size of the tumor is reduced in order to preserve renal function and avoid dialysis. In patients with chronic renal failure caused by bilateral nephrectomy, ongoing treatment with dialysis support can be achieved through the choice of effective drugs and knowledge of their pharmacokinetics and pharmacodynamics.