Oxidative polymerization of pyrrole (Py) has been studied in the presence of poly(vinyl methyl ether) (PVME) and crosslinked PVME microgels using FeCl3 as oxidant and water or aqueous ethanol as a dispersion medium. The influences of the reaction medium and oxidant addition mode on the morphology as well as properties of final particles are discussed. SEM images of dispersions prepared in the presence of uncrosslinked PVME in water or water/ethanol mixtures indicate small spherical particles (40-100 nm). Large needle-like polypyrrole particles (approximately 400 ran long; aspect ratio 8:1) are formed in aqueous ethanol in the presence of crosslinked PVME microgels at Py/PVME ratio higher than 2:1.