Collagen extracted from tissues by alkaline treatment has a different isoelectric point (pI approximate to 5) than the commonly-used acid-or pepsin-treated collagen (pI approximate to 9). In this study, the feasibility of using the alkali-treated collagen (AC) as a carrier of basic fibroblast growth factor (bFGF) for enhancement of angiogenesis was examined. AC hydrogels were prepared by chemically crosslinking AC molecules using glutaraldehyde (GA). We investigated the effects of GA concentration in AC gels on the degree of swelling of the gels in an aqueous environment and on the in vivo degradation rate of the gels. Horse cytochrome c (pI: 9.6), a model for bFGF (pI: 9.6), electrostatically adsorbed to the AC gels. Subcutaneously-implanted AC gels incorporating bFGF led to enhanced angiogenesis compared with bFGF-free gels. Thus, AC gels incorporating bFGF appear to be useful materials for (i) the enhancement of angiogenesis and (ii) tissue engineering scaffolds.