Syndiotactic (st-) poly(methyl methacrylate) (PMMA) with a hydroxy group at the chain end (st-PMMA-OH) was prepared by st-living polymerization with t-C4H9Li/(n-C4H9)(3)Al in toluene at -78 degrees C. The resulting st-PMMA-OH was fractionated into uniform polymers by means of supercritical fluid chromatography. Uniform st-PMMA-OH with degree of polymerization of 26 was reacted with 1,3,5-benzenetricarbonyl trichloride as a coupling agent and the three-arm star polymer uniform with respect to branch length was isolated from the reaction mixture by the aid of gel permeation chromatography (GPC). Viscometric property of the uniform star PMMA was studied in some detail by using a GPC-differential viscometer.