X-ray diffraction, SEM analysis, Mössbauer spectroscopy and magnetic measurements were used to characterize three different magnetic beads (Dynabeads®). Maghemite (γ-Fe2O3) is the predominant crystalline phase. The nanoparticles were evenly spread in the beads, and the crystal sizes were in the range of 8 nm. The nanoparticles showed superparamagnetic behaviour. The particle's intrinsic magnetization of about 340 kA/m is typical for nanoparticles of maghemite.