A guiding catheter was used in seven patients who underwent balloon dilation of nine renal arteries. The advantages of using a guiding catheter for renal angioplasty are analogous to the benefits obtained with a coronary angioplasty guiding catheter used in coronary angioplasty. The guiding catheter provides back-up support to cross lesions and allows selective contrast visualization of the lesion before, during, and after dilation. It is also possible, when using a guiding catheter, to measure pressure gradients across lesions without having to recross the lesion which may help to ensure that adequate dilation of the stenosis has been accomplished.