The polyaniline (PANI) dispersions have been prepared in acidic aqueous media by oxidative dispersion polymerization in the presence of a polymeric stabilizer. The polymeric stabilizer used in this study is the poly(methyl vinyl ether-alt-maleic acid) (PMVEMA) which contains acid groups (-COOH). The PANI-PMVEMA particles have a uniform size and a spherical shape. The PMVEMA dispersions show almost no desorption of the PMVEMA, even though the sonication at 500 W for 20 min and the centrifugation at 500 rpm for 60 min are performed 10 times. The existence of the PMVEMA on the surface is confirmed by X-ray photoelectron spectroscopy. The dispersion stability of the PANI-PMVEMA dispersions is extensively influenced by zeta potential which was governed by the acid group (-COOH) of the PMVEMA on the PANI-PMVEMA particle surface.