Background. We report the case of a male infant whose right kidney migrated to an ectopic position after birth. The migration of a kidney in postnatal life without any symptoms has not been reported in literature so far. Case Presentation. In a series of antenatal and the first postnatal ultrasound scans, the right kidney was normally located within the right renal fossa. During the first 3 months of life, the kidney migrated to a subdiaphragmatic position. This was confirmed on MRI scan. The infant was asymptomatic with normal renal function and blood pressure. Conclusion. Postnatal migration of a kidney has been described in cases of diaphragmatic hernia or nephroptosis. In this report, we describe a case of kidney migration where there were no underlying anatomical defects to provide an explanation for the kidney migration. This is the first report in literature of a case of postnatal migration of a kidney.