Abstract: A cement for fixing a bone prosthesis, the cement containing:(a) a solid phase comprising firstly polymethylmethacrylate and a copolymer of methyl methacrylate with an acrylate or a methacrylate of another alcohol, both in powder form, and secondly an organic peroxide suitable for generating free radicals; and(b) a liquid phase comprising methyl methacrylate and an accelerator for accelerating decomposition of the organic peroxide.The copolymer is an oligomer, and the liquid phase includes as the accelerator for accelerating decomposition of said organic peroxide an acrylate or a methacrylate carrying a tertiary amine function, and as a cross-linking agent a compound having at least two functions in its molecule suitable for reacting with the reactive functions carried by the polymers of the solid phase, or else a double bond and a function suitable for reacting with the reactive functions carried by the polymers of the solid phase.