In this study, we found stereospecific free-radical polymerization of an ionic vinyl monomer such as methacrylic acid calcium salt (MAA-Ca) in organic solvents for facile preparation of isotactic-rich polymers. The polymerization of MAA-Ca was performed with 2,2'-azobisisobutyronitrile (AIBN) as an initiator in N,N-dimethylformamide (DMF) under argon atmosphere at 60 degrees C. The obtained poly(MAA - Ca) was converted into poly(methyl methacrylate) (PMMA), which contained approximately 60% of the mm triad (mm/mr/rr = 59/33/8). When free- radical polymerization of MAA - Ca was carried out in toluene/DMF(2:1) mixed solvent, the mm triad of the resulting PMMA (mm/mr/rr = 65/30/5) was increased more than that of the polymer obtained in DMF. These results indicate that the ionic interaction affected stereocontrol in the free-radical polymerization of MAA-Ca for production of the isotactic-rich polymers.