Background: During hemodialysis session, several adverse reactions can occur on platelets, which are attributable to bioincompatibility of the dialysis membrane. Glycoprotein IIb/IIIa (GPIIb/IIIa) is the receptor for fibrinogen, which mediates platelet aggregation and adhesion. Accordingly, we compared the influence of a cellulose triacetate (CTA) and polysulfone (PS) membrane on GPIIb/IIIa and platelet activation. Methods: Blood samples from 5 patients on hemodialysis were taken at 0 time, 15 min, 30 min, 60 min and 240 min, during a single hemodialysis session, by a crossover design using CTA or PS. Platelet count and plasma concentration of GPIIb/IIIa, β-thromboglobulin (β-TG) and platelet factor 4 (PF-4) were measured. GPIIb/IIIa was measured by flow cytometry. β-TG and PF-4 were measured by ELISA. Results: There was no significant change in the total amount of GPIIb/IIIa during dialysis session between the CTA and PS. However, the level of bound GPIIb/IIIa was significantly (p < 0.0002) increased from 1,426 ± 435 to 40,446 ± 2,777 mol/PLT with PS. In contrast, there was no significant change with CTA (3,258 ± 1,469 to 4,301 ± 1,422 mol/PLT). The platelet counts and β-TG and PF-4 behavior during the dialysis session did not show significant change between the PS and CTA. Conclusion: The characterization of changes in platelet membrane receptor (GPIIb/IIIa) may be a useful marker for studying the biocompatibility of dialysis membranes. On platelet aggregation, CTA might be more biocompatible membrane than PS.