Fibrinogen as well as collagen, cell adhesive proteins, were adsorbed efficiently onto a heparin-based hydrogel. The physisorption of these proteins was strong and stable so that the bound proteins were not easily released from the hydrogel at physiological condition. After the physisorption of fibrinogen or collagen type I onto the hydrogel, National Institute of Health/3-day transfer, inoculum $3{ imes}10^5$ cells (NIH/3T3) fibroblasts attached and spread well on the hydrogel, whereas the bare hydrogel or serum treated hydrogel showed poor cell attachment. Cell proliferation was also remarkably enhanced by the physisorption of these cell adhesive proteins, similar to that on tissue culture plate.