The nephroblastoma or Wilms tumor (WT) is the most common renal tumor in childhood, representing approximately 6-7% of all pediatric cancers, with a yearly incidence of 10 cases in one million children less than 15 years old, and continues to arouse interest by remarkable actual therapeutic successes, consecutive to the multidisciplinary approach. Its maximum incidence is around the age of 3-3.5 years old, having an equal frequency in males and females. We present the case of a child, aged three years and five months, who was diagnosed with WT (nephroblastoma) with triphasic pattern, stage II tumor, and admitted to the Department of Oncopediatry for chemotherapeutic treatment and clinico-biological investigations.