Changes in the macromolecular parameters of trypsin in the presence of 2-chloroethanol in aqueous solutions have been studied by means of optical and hydrodynamic methods. At temperature--dependent volume fraction of 2-chloroethanol in solution upsilon t < 0.30 the globular structure of trypsin is destroyed but the regularity of polypeptide chains within the limits of secondary structure is maintained. At 0.30 < upsilon < 0.80 the solvation envelope of macromolecules is kept constant mainly owing to hydration, but the solubilization takes place only at upsilon < 0.30. At upsilon < 0.80 spiralization sharply increases and reaches in pure 2-chloroethanol its maximum value (50%). The intrinsic viscosity moreover reaches only half the whole value [eta]coil--[eta]glob.