This book is focused on interactions of hyaluronan (HA) and bovine serum albumin (BSA). These interactions were studied by the SEC-MALLS method, where molar mass, root mean square (rms) radii, hydrodynamic radius and intrinsic viscosity of particles of the system were defined. Additionally, interactions were examined by measurement of DLS and zeta potential, where hydrodynamic radius and a value of the zeta potential were defined. The interactions were confirmed at any of the used media, but with different efficiency. Furthermore it was found out, that the high ionic strength minimizes the range of the interactions, magnifies the radii of the complexes, their intrinsic viscosity and zeta potential. It was proved that complexes become smaller in their radii and viscosity with growing BSA concentration.