The problem of cryoglobulins role in different diseases is very actual. Our preliminary investigations showed that activation energies of protein transition from the cryocomplex into solution correlate with clinical symptoms of cryoglobulinemia. The average meaning of activation energy show that the main type of interaction between the molecules in cryocomplexes is of Van-der-Vaalse type. The dependence of light scattering intensity on the temperature of the serum of patients with hepatitis C virus infection and cryoglobulinemia have been studied. From these data the activation energies of protein transition from the cryocomplex into solution have been calculated. The activation energies correlate with clinical symptoms of cryoglobulinemia. Low activation energies (2.6 +/- 1.4 kDg/M) accompany the kidney damage. If cryoglobulin level is not low at high activation energies the kidney damage is severe due to cryoimmunocomplex deposition in organ.