Various hydrogels without modification by any cell adhesive proteins have been investigated as cell scaffolds. The present study shows that bovine fetal aorta endothelial cells can adhere, spread, proliferate, and reach confluence on poly(acrylic acid), poly(sodium p-styrene sulfonate), and poly(2-acrylamido-2- methyl-1-propanesulfonic sodium) gels, whereas cells reach subconfluence on poly(vinyl alcohol) and poly(methacrylic acid) gels. The proliferation behavior was sensitive to both hydrogel charge density and crosslinker concentration. The relationship between cell proliferation and zeta potential of gels was discussed. It was found that hydrogels with a negative zeta potential higher than about 20 mV facilitates cell proliferation.