Polyethers were studied as potential materials for vascular prostheses. By crosslinking poly(tetramethylene oxide) (PTMO) with poly(ethylene oxide) (PEO), hydrophilic networks were obtained containing PTMO as well as PEO. Attempts were made to reduce the crystallinity and melting point of PTMO because of the required elastomeric behaviour at body temperature. Compared to non-crosslinked PTMO, crosslinking in the melt resulted in a decrease in the melting point from 43·7 to 38·7°C and a decrease of the crystallinity from 46 to 28%. By copolymerizing tetrahydrofuran with oxetane or dimethyloxetane, melting points below 38°C were obtained, together with crystallinities lower than 20%.