We present a case of a 17-year-old pregnant girl, with hematuria. Magnetic resonance imaging showed a solid left renal mass. The patient had a radical nephrectomy during the 20th week gestation and the diagnosis was nephroblastoma. She gave birth to a healthy child at term and refused adjuvant treatment. She is disease-free after 24 months of follow-up. Based on the excellent results achieved while treating children with Wilms' tumor using surgery, chemotherapy and radiotherapy, adults with the same disease should be treated similarly. This treatment must be instituted early, even in pregnant women.