Molecular mass of the iron-dextran complex (M(w) = 1133 kDa), diameter of its particles (similar to 8.3 nm) and the content of iron ions in the complex core (N(Fe) = 6360) were determined by static light scattering, measurements of refractive index increment and the Cotton-Mouton effect in solution. The known number of iron ions permitted the calculation of the permanent magnetic dipole moment value to be mu(Fe) = 3.17 x 10(-18) erg Oe(-1) and the determination of anisotropy of linear magneto-optical polarizabilities components as Delta chi = 9.2 x 10(-21) cm(3). Knowing both values and the value of the mean linear optical polarizability alpha = 7.3 x 10(-20) cm(3), it was possible to show that the total measured CM effect was due to the reorientation of the permanent and the induced magnetic dipole moments of the complex. Analysis of the measured magneto-optical birefringence indicated very small optical anisotropy of linear optical polarizability components, kappa(alpha), which suggested a homogeneous structure of particles of spherical symmetry. (C) 2011 Elsevier Inc. All rights reserved.