Polyacrylonitrile (PAN) is a synthetic biocompatible polymer used as a filtering membrane in hemodialysis and for enzyme immobilization purposes. However, its potential usage in other medical applications is limited due to its poor hydrophilicity. To overcome this problem, two groups of electrospun PAN fibers were treated with sodium carbonate (Na2CO3) and sodium hydroxide (NaOH), respectively at 100 degrees C for 5 minutes. Fibrin gel was then coated onto the treated samples before seeding human umbilical vein endothelial cells (HUVECs) for 1 and 3 days. X-ray diffraction results showed increased crystallinity of the PAN fibers when treated with Na2CO3 and NaOH. The contact angle measurements showed that the hydrophilicity of Na2CO3 treated and NaOH treated samples improved from 115 degrees to 88 degrees and 64 degrees, respectively. The Fourier transform infrared spectroscopy confirmed that their hydrophilicity was due to the existence of carboxyl and hydroxyl groups. However, tensile strength of the PAN fibers was reduced by 34% when treated with Na2CO3 and 42% when treated with NaOH. Cytotoxicity tests showed increased absorbance in day 3 for both treated samples. However, the absorbance value for NaOH treated PAN fibers and Na2CO3 treated PAN fibers showed nearly the same absorbance on day 7. In vitro tests showed increased cell adhesion and proliferation after 3 days of culture. The PAN treated fibers coated with fibrin are, therefore, proven to attract HUVEC cells and promote endothelialization.