Polyethersulfone (PES) membranes are widely used in medical devices, especially intravascular devices such as intravascular bioartificial pancreases. In the current work, the pure PES and PES-pyrolytic carbon (PyC) composite membranes were synthesized and permeability studies were conducted. In addition, the cytocompatibility and hemocompatibility of the pure PES and PES-PyC membranes were investigated. These materials were characterized using peripheral blood mononuclear cell (PBMC) activation, platelet activation, platelet adhesion, ß-cell viability and proliferation, and ß-cell response to hyperglycemia. The results showed that platelet activation decreased from 87.3% to 27.8%. Any alteration in the morphology of sticking platelets was prevented, and the number of attached platelets decreased by modification with PyC. The 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide assay corroborated that PBMC activation was encouraged by the PyC-modified PES membrane surface. It can be concluded that PES-modified membranes show higher hemocompatibility than pure PES membranes. ß-cells cultured on all the three membranes displayed a lower rate of proliferation although the cells on the PES-PyC (0.1 wt. %) membrane indicated a slightly higher viability and proliferation than those on the pure PES and PES-PyC (0.05 wt. %) membranes. It shows that the PES-PyC (0.1 wt. %) membrane possesses superior cytocompatibility over the other membranes.