Hemodialysis ("HD") has been suggested as a risk factor for stent thrombosis. However, platelet function in HD patients after coronary stent implantation remains unclear. The aim of this study was to evaluate platelet function following coronary stent implantation in HD patients. A total of 10 HD and 31 non-HD patients who underwent a first coronary stent implantation were studied. All patients received 100 or 200 mg of asprin and thienopiridine (either ticlopidine 200 mg or clopidogel 75 mg) daily. Platelet function was assessed 2-6 weeks (21 ± 8 days) after stent implantation by: (1) platelet maximal aggregation, using light transmittance aggregometry; (2) platelet aggregation threshold index, which was defined as putative concentration of agonist giving 50% maximum aggregation using whole-blood aggregometry; and (3) platelet activation markers (PAC-1 and CD62p), using whole blood flow cytometry. There were no differences between the two groups in baseline and procedure characteristics, except for a greater prevalence of hypertension and calcification in the HD group. Early stent thrombosis and bleeding did not occur in either group. Although no differences in platelet maximal aggregation or whole-blood aggregation were observed, expression of PAC-1 (39.6 ± 9.1 vs 24.2 ± 13.2%) and CD62p (10.4 ± 5.5 vs 5.4 ± 2.3%) were significantly increased in the HD group compared with the non-HD group. HD patients exhibited enhanced platelet activation after coronary stent implantation, but suppression of platelet aggregation was achieved by the current dual antiplatelet therapy.