[en] Compared to conventional ferrofluids, which contain mostly spherical particles, a dispersion of highly anisometric particles such as rods or chains is expected to give rise to an enhancement or modification of well-known ferrofluid properties. This contribution reports on the synthesis of a ferrofluid containing stable chains of iron nanoparticles and on its microstructural characterisation by means of transmission electron microscopy and small-angle X-ray scattering (SAXS). The SAXS measurements develop a pronounced anisotropy of the scattering pattern as a function of an increasing external magnetic field. Evaluation of the radially averaged SAXS curves in terms of basic scattering functions is discussed.