Biocompatible diphasic compositions are prepared comprising a dispersed phase suspended in a continuous phase, more particularly suitable for use as a filling material in reparative and plastic surgery. The dispersed phase consists of particles of at least one hydrogel of a (co)polymer obtained by polymerizing and cross-linking acrylic acid, methacrylic acid and/or at least one derivative of said acids. The continuous phase is an aqueous solution or hydrogel of a polymer selected from proteins, polysaccharides and their derivatives which have been cross-linked. The polysaccharide may be hyaluronic acid, its salts and a mixture of its salts, advantageously consisting of a sodium hyaluronate.
