The surface structures of three kinds of poly(ethylene oxide)-segmented nylon (PEO-Ny) films prepared by the solvent-cast method were investigated with electron spectroscopy for chemical analysis (ESCA). The PEO-Ny's used were high-crystalline PEO-segmented poly(iminosebacoyliminohexamethylene), low-crystalline PEO-segmented poly(iminosebacoylimino-m-xylene), and amorphous PEO-segmented poly(iminoisophthaloyliminomethylene-1,3-cyclohexyienemethylene), and the PEO contents in the bulk polymers were approximately 10 wt %. The ESCA results showed that the PEO segment was enriched on the top Surfaces of all the films, and the degrees of enrichment were different. The mechanism of the PEO enrichment,as examined.