A newborn female infant with marked bilateral renal enlargement resulting from an absolute increase in renal parenchymal mass is described. The number of renal lobes was increased and there was persistent subcapsular glomerulogenesis. In addition, the lungs manifested delayed maturation and contained multiple small cysts. Although the renal growth disturbance resembled that sometimes found in hemihypertrophy and the Beckwith syndrome, the associated pulmonary lesions and the absence of other anomalies make this patient distinctive.