OBJECTIVE--To examine the use of balloon angioplasty in the treatment of native adult aortic coarctation. DESIGN--Haemodynamic and angiographic studies to establish the diagnosis of aortic coarctation were established before carrying out the procedure in all patients. SETTING--All the studies and angiographic procedures were performed in a large district general hospital within the departments of cardiology and radiology. There was careful perioperative monitoring. The mean hospital stay was three days. PATIENTS--15 adult patients (with clinical, haemodynamic, and angiographic evidence of native aortic coarctation) were considered for this treatment. 13 were offered balloon angioplasty. One was excluded, as there was no significant gradient across the lesion. One patient had complete atresia at the site of the coarctation. INTERVENTIONS--Percutaneous transluminal balloon angioplasty was carried out with balloon catheters diameter 2 mm less than the diameter of the aorta immediately below the left subclavian artery to minimise the possibility of tearing the aortic wall. MAIN OUTCOME MEASURES--Abolition or significant reduction of the preoperative gradient was achieved in all 13 patients treated. Reduction in blood pressure of the upper limb was also achieved in all of the patients. Only four patients required continued antihypertensive treatment. Two patients developed false aneurysms after the procedure and required surgery. No deaths occurred. These results compare favourably with conventional surgery and are much more economical. CONCLUSIONS--Balloon angioplasty could become the first line treatment for all patients with native adult aortic coarctation, but longer term follow up is required to validate this.