BACKGROUND The increased bleeding tendency of chronic renal failure (CRF) patients has been attributed to platelet dysfunction. However, reports on various platelet functions in uraemic patients have been conflicting. The present study sought to analyse platelet function by examining their surface glycoproteins in well-identified populations of CRF patients. METHODS Three groups were studied: 22 chronic haemodialysis (HD) patients, 25 conservatively treated patients with CRF and 30 controls. Bleeding tendency was assessed by measuring bleeding time and by recording current haemorrhagic symptoms. We measured the fibrinogen receptor GPIIbIIIa, the von Willebrand receptor GPIb, and P-selectin levels on the platelet surface using flow cytometry. RESULTS Forty percent of CRF and 45% of HD patients had bleeding. The bleeding time was similar in the HD and CRF groups, but was longer in both groups than in controls. In resting platelets, GPIb expression was lower in CRF patients than in controls. In stimulated platelets (i) GPIb expression was higher in HD patients than in both controls and CRF patients; and (ii) GPIIbIIIa and P-selectin expression were lower in CRF and HD patients than in controls. CONCLUSIONS These findings indicate that uraemic platelets are hyporesponsive to stimulation.