The grain-size dependence (250 down to <5 &mgr;m) of the hysteresis properties of a natural magnetite and a natural titanomagnetite were determined with an Alternating Gradient Magnetometer. In addition to the classical hysteresis parameters (Mr/Ms1,Hc,Hcr,Hcr/Hc): three additional hysteresis parameters (MDFhys, MIFhys and &khgr;hys) were obtained from the loops (von Dobeneck, 1993). The classical hysteresis parameters agree well with data of Hartstra (1982), indicating that the small sample size of the AGM specimens does not hinder acquisition of meaningful data. The additional hysteresis parameters seem to depend on mineralogical composition but show little grain-size dependence. &khgr;hys/&khgr;lf is ~1.6 for coarse grain-size fractions and decreases with grain size in fine fractions. The onset of the decrease corresponds to the PSD-MD transition. ¿ American Geophysical Union 1996