PEG-based and PEPG-based polyurethane (PU) hydorgels were prepared using various ratios of ethylene oxide (EO)/propylene oxide (PO) and their swelling behaviors inverstigated. The PEG-based PU hydrogels showed a continuous volume transition with temperature. In contrast, The swelling behaviors of the PEPG-based PU hydrogels with a higher PO content exhibited a more sensitive volume transition than those of the PEPG-based PU hydrogels with a lower PO content. In a pulsatile swelling behavior experiment, the swelling-deswelling rates of the PEG-based PU hydrogels were constant regardless of the PEG molecular weight. In contrast, swelling-deswelling rates of the PEPG-based hydergels with a higher PO content were faster than those of the PEG-based PU hydrogel. This suggests that PO increases the hydrophobicity of the gel. Flory''''s interaction parameter,χ, was employed to characterize the relative solvent-polymer interaction. There are two contributions to the interaction parameter,χ, the entropic (χ_S) and the enthalpic (χ_H) contribution. The result of this study showed that the major contribution to the polymer-water interaction parameter χ_S.