The introduction of 5F and even 4F catheters allows transradial coronary arteriography and aortography. The efficacy and limitation of angiography via the radial artery using 5F catheter was prospectively evaluated in 200 consecutive patients. Cardiac catheterization with diagnostic angiography was successfully performed in 198 of 200 patients, including 11 patients with acetylcholine provocation test, 21 with bypass graft angiography, 38 with aortography and 5 with biopsy of the left ventricular myocardium. The transradial approach was not indicated in one patient without normal Allen's test and in one with weak radial pulse. In four patients, guide wire support was needed during manipulation because of marked tortuosity in the innominate artery. The sheath was removed immediately after the completion of the procedure, followed by 5 hours of tourniquet hemostasis without manual compression. The postoperative resting period was reduced. Peripheral vasospasm occurred in 2.5% of cases, but could be eliminated by administration of isosorbide dinitrate and lidocaine. Subcutaneous hemorrhage in the puncture site was observed in 3.0% of cases, but required no additional compression. Transradial catheterization is a minimally invasive, safe and practical alternative to the brachial or femoral artery approach in patients with normal Allen's test.