Relationships between surface tension and solubility parameter, and between critical surface tension and dispersion component of solubility parameter of polymers were determined by using a modified Hildebrand-Scott equation. Non-polar polyethylene, strongly polar nylon 6, and weakly polar polyethylene terephthalate were used as model polymers. Polymer films of different crystallinity were prepared by annealing, and their surface tension, including dispersion and polar components were determined from the content angle data by the Kaelble method. The solubility parameter components of the polymer films were calculated from the modified Hildebrand-Scott equation. In addition, the effect of crystallinity on the solubility parameter was examined in relation to the crystal structural and conformational changes of the polymer film. -- AATA