Percutaneous balloon occlusion of a large hypertensive idiopathic renal arteriovenous fistula is reported. A lumbar thrill was noted in a 52-year-old hypertensive woman. Intravenous digital substraction angiography identified the lesion. After arteriographic assessment a percutaneous embolisation was performed with a releasable balloon positioned on a coaxial micro-catheter. Immediate post-procedural angiographic control demonstrated complete occlusion with a small segmental area of renal hypoperfusion. The lumbar thrill disappeared. Normalisation of the blood pressure was noted two days later and confirmed eight months later. Persistent occlusion of the fistula was angiographically confirmed, whereas the area of renal hypoperfusion had partially decreased. Releasable balloon percutaneous embolisation appears to be a safe alternative to surgery in the treatment of large renal arteriovenous fistulas.