Severe aortic valvar stenosis in early infancy has generally been treated by surgical valvotomy or balloon valvoplasty. Due to previous femoral arterial complications, we changed our practice in infants <5 kg by using an axillary arterial cut down. Balloon valvoplasty using this approach was performed in 22 consecutive infants aged from 1 to 77 days, with a mean age of 17 days, all having severe aortic valvar stenosis. Their weight was between 2 and 4.46 kg, with a mean of 3.28 kg. Left-ventricular function was normal in 13, mildly reduced in 3, and moderately reduced in 6 infants, with 3 requiring inotropic support. Aortic valvar diameter, as measured echocardiographically, varied from 5.2 to 8.5 mm with a mean of 6.43 mm, and the mean velocity across the aortic valve was 4.10 m/s, with a range from 1.6 to 5.5 m/s. Balloon valvoplasty was performed via a right axillary artery cut down using a 4 French sheath, though occasionally a bare Tyshak balloon catheter was inserted directly. The diameter of the balloon was equal to or within 1 mm of the aortic valvar diameter. The arteriotomy was repaired with interrupted 6/0 Prolene sutures. Minimal or no angiography was undertaken, with a mean screening time of 9.8 min. Results: Balloon valvoplasty was achieved in all the infants. The gradient prior to intervention ranged from 50 to 125 mmHg, with a mean of 77 mmHg and was reduced to between 10 and 60 mmHg, with a mean of 30 mmHg, following balloon valvoplasty. Echocardiography after the procedure showed 9 patients with no aortic regurgitation, 2 with trivial, 10 with mild, and 1 with moderate to severe aortic regurgitation. The volume of the pulse in the right arm was normal in the 13 of the 22 infants immediately following intervention. Only 2 of the remaining 9 infants required an intravenous infusion of Heparin to maintain patency of the axillary artery. One patient experienced axillary arterial transection requiring microsurgical repair. There was 1 death. This infant had significant left-ventricular hypoplasia and, in retrospect, may have been better managed by a Norwood operation. All patients have been followed up for a mean of 37.3 months, with a range from 7 months to 9 years. Repeat valvoplasty was necessary in 3 patients. Subsequent surgical intervention was needed in 3, consisting of 2 surgical valvotomies, one combined with mitral valvar replacement, and 1 Ross procedure at the age of 3 months. The brachial pulse in the right arm was decreased in 2 infants, and absent in 2. Conclusion: Aortic valvoplasty via an axillary arterial cut down is a safe and effective method, comparing favourably to access via the femoral artery. This approach aids rapid crossing of the aortic valve in these haemodynamically unstable patients. Axillary arterial compromise may occur, but appears to be less important than femoral arterial compromise, and needs further evaluation.