Electrospun nanofibers of poly (2-methacryloyloxyethyl phosphorylcholine) (MPC) possessing excellent hemocompatibility were successfully fabricated first. These nanofibers were investigated as drug-delivery vehicles for suppressing the acute thrombogenicity of vascular grafts to lower the risk of coronary artery disease by improving the graft patency rate; the graft patency rate is the percentage of patients who do not have any blockage in a graft after a stent-graft treatment. We varied the MPC concentrations in ethanol from 1 to 10 wt % to fabricate electrospun MPC fibers. Scanning electron microscopy images revealed that when the MPC concentration was lower than 5 wt %, beads instead of fibers were formed. When the MPC concentration was increased (>5 wt %), uniform fibers were produced with average fiber diameters of about 160 nm (5 wt %), 640 nm (7.5 wt %), and 1270 nm (10 wt %). In vitro drug-release tests showed that a higher amount of drugs was diffused from MPC fibers with small diameters; this indicated a faster drug-release rate for the thinner MPC fibers. Diameter-controlled MPC fibers could be used as a new vascular graft materials. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40606.