We describe a 23 months old boy who presented a clinical picture of bronchial hyperreactivity and a tumoral intrathoracic mass in a plain thorax X-ray, receiving for these reasons, antibiotic therapy during 30 days. Intravenous pyelography and ultrasonography revealed the presence of an ectopic intrathoracic kidney. Since this renal anomaly is usually asymptomatic and do not requires treatment, it is necessary to suspect this abnormality whenever an intrathoracic mass is found.