The effects of nucleating agent on nonisothermal crystallization were examined for syndiotactic polystyrene (SPS) using Differential Scanning Calorimetry (DSC). The crystallization peak temperature T-c, the crystallization rate parameter (CRP), the enthalpy of crystallization and melting, and the recrystallization behavior were compared between organic (DMBS, 1,3,2,4-dis-5-(3,4-dimethyl benzylidene) sorbitol) and inorganic (talc) nucleating agents. Both of the nucleation agents promoted the crystallization rate of SPS until some critical concentration of about 3,000 ppm. DMBS worked more effectively as a nucleating agent than talc, although the T-c showed lower level in SPS/DMBS than SPS/talc.