Crosslinked poly(2-hydroxyethyl methacrylate)-based magnetic microspheres were prepared in a simple one-step procedure by dispersion polymerization in the presence of several kinds of iron oxides. Cellulose acetate butyrate and dibenzoyl peroxide were used as steric stabilizer and polymerization initiator, respectively, and ethylene dimethacrylate was a crosslinking agent. The resulting product was characterized in terms of particle size, particle size distribution, iron(III) content, and magnetic properties. In the presence of needle-like maghemite in the polymerization mixture and under suitable conditions, magnetic microspheres with relatively narrow size distribution were formed. An increase in the particle size and, at the same time, a decrease in molecular weight of uncrosslinked polymers resulted, as the continuous phase became richer in 2-methylpropan-1-ol. Coercive force of needle-like maghemite-containing particles was higher than that of cubic magnetite-loaded microspheres. Coercive force increased with the decreasing iron content in the particles.