Fabry disease is a lysosomal storage disorder with kidney involvement. The initial manifestation of kidney disease is often impaired urinary concentrating ability in adolescence or young adulthood. We describe a boy diagnosed prenatally with Fabry disease who presented with polyuria, polydipsia, hypertension, hypokalaemia and proteinuria at 7 years of age. A formal water-deprivation test followed by vasopressin challenge confirmed nephrogenic diabetes insipidus. A renal biopsy revealed findings typical of Fabry disease. Angiotensin converting-enzyme therapy resulted in rapid improvement of symptoms, normalization of blood pressure and resolution of hypokalaemia and proteinuria. This child is the youngest reported Fabry disease patient with documented renal pathology and clinical manifestations of hypertension, proteinuria and nephrogenic diabetes insipidus.