Two different microrheological. characterization techniques for the microstructure of complex fluids (i.e. rheomagnetic and rheooptic measurements) were adopted to study the microstructural state of magnetic particle suspensions. These two techniques measure the dispersion state of various single-domain magnetic particles (rodlike gamma-Fe2O3 or CrO2 and platelike Ba-ferrite). The techniques complement one other by measuring the order parameter for the magnetic particles in suspension over different concentration ranges. The rheomagnetic measurement is good for on-line characterization of microrheological properties of magnetic particle suspensions. The rheooptical measurement is useful for off-line dispersion microstates and rheological properties of the suspensions.