Dynamic viscoelastic measurements were made on ovalbumin gels prepared by two different thermal denaturation methods for a study of their gel structures. Results are discussed in the light of the fractal concept developed for the critical gel structure of synthetic polymers at the sol-gel transition point. Especially, a role of added salt on association kinetics of denatured proteins as well as on the resulting gel structures are described in detail. (C) 1998 Elsevier Science Ltd. All rights reserved.