Myosin, fibrinogen, and myosin-fibrinogen gels formed by heating at a rate of 12 °C/h were disrupted with guanidine hydrochloride, urea, and 2-mercaptoethanol. The degree of disruption was quantitated by turbidity, and complexes that remained soluble were analyzed by gel filtration in 6 M guanidine hydrochloride and SDS-polyacrylamide gel electrophoresis. Myosin and fibrinogen together or individually formed gels at 70 °C that were more difficult to solubilize than gels formed at 50 °C. Myosin and fibrinogen gels formed at 70 °C were stabilized by both noncovalent and disulfide bonds. Noncovalent and disulfide bonds are formed in myosin-fibrinogen gels at 50 and 70 °C.