Ectopic kidney is a rare condition. Giant hydronephrosis is also an uncommon lesion in children and is usually due to ureteropelvic junction obstruction. We report a case of 7-year-old girl presenting with abdominal fullness. The imaging characteristics of magnetic resonance urography of the lesions are reported. The findings from the radiologic investigations were suggestive of a dysplastic ectopic pelvic kidney with giant hydronephrosis. Subsequent surgery confirmed the diagnosis. An ectopic kidney with giant hydronehrosis is an extremely rare condition in children and can present as an asymptomatic abdominal mass. A careful survey for other structural anomalies is mandatory in such cases.
