Syndiotactic polystyrene (s-PS) and atactic polystyrene (a-PS) were melt-spun into filaments. The s-PS filaments exhibited increasing amounts of crystallinity and orientation with increasing drawdown ratio and spiriline stress. The a-PS filaments were amorphous but exhibited birefringence. The birefringence and Hermans orientation factors for a-PS were proportional to this spinline stress. In ice water and at low drawdown ratios, the s-PS is glassy or mesomorphic. At higher drawdown ratios and spinline stresses, it crystallized. The crystalline form was the zigzag TTTT hexagonal alpha-form. The birefringence and orientation factors of the s-PS filaments were higher than those of the a-PS filaments and the difference of the birefringence increased with increasing spinline stress. Mechanical testing results showed that the Young's modulus and tensile strength generally increased with increasing spinline drawdown ratio for both a-PS and s-PS filaments. The elongation to break was enhanced for both materials by increased chain orientation. (C) 2004 Society of Plastics Enghieers.