The purpose of this study was to evaluate feasibility, safety, and efficacy of implantation of unsheathed Palmaz-Schatz coronary stents via the radial artery. Anticoagulation after coronary stenting has the hazard of vascular complications if large-bore guiding catheters are introduced via the femoral artery. Such complications have serious local sequelae, are associated with suboptimal anticoagulation, and prolong hospitalization. By combining 6F guiding catheters and low-profile dilatation catheters with bare Palmaz-Schatz stents, smaller vessels such as the radial artery can be selected as the entry site. It is postulated that no major puncture site-related complications occur because hemostasis is easily achieved and no veins and nerves are near the radial artery. With double blood supply to the hand, radial artery occlusion is well tolerated. Twenty-five bare Palmaz-Schatz stents were implanted via the radial artery through 6F guiding catheters in 20 consecutive patients for venous bypass graft stenosis (n = 9; 45%), native coronary artery restenosis (n = 7; 35%) and suboptimal transradial artery PTCA (n = 4; 20%). Immediately after stent implantation and assessment of the result by means of computerized quantitative coronary analysis, the arterial sheath was withdrawn followed by intense anticoagulation and free ambulation of the patient. Radial artery function and anatomy were assessed by two-dimensional and Doppler ultrasound examination. Lesions (n = 24) were of type A (n = 13; 54%), B (n = 6; 25%) and C (n = 5; 21%). The reference diameter of the stented segments was 3.2 +/- 0.5 mm (2.2 to 4.2 mm).(ABSTRACT TRUNCATED AT 250 WORDS)