Abstract: The invention relates to an uncrosslinked hydrogel, its process of preparon as well as its uses as an article for medical and/or surgical purposes such as tubes, filaments, films, joints, implants and the like, especially in ophthalmology. The uncrosslinked hydrogel has a relatively high water content and is constituted from a liquid starting composition which comprises 2 to 50% of a copolymer of acrylonitrile and an olefinically unsaturated comonomer bearing aninic groups, possible salified, the molar ratio arcylonitrile-comonomer being comprised between 90:10 and 100:0, a suitable solvent and a suitable non-solvent of said copolymer. The ratio solvent/non-solvent is comprised between 500:1 and 0.5:1 by weight, said hydrogel having a microporous structure, an ionic capacity comprised between 0 and 500 mEq/kg of gel, a hydric content compressed between 50 and 98% and having an aptitude for permanent deformation under stress, even at a temperature below 40.degree. C.