This paper describes a technique for monitoring polymerisation of acrylic bone cements by measuring changes in the characteristics of the transmission of ultrasound through the cement brought about by the polymerisation reaction. To the authors’ knowledge, this is the first time that a technique for the continuous monitoring of the mechanical properties of polymerising bone cement has been presented. The cement exhibits the expected behaviour of low modulus until approximately 300-450s from the time of mixing, after which a period of rapid polymerization occurs. In future work, we aim to extend the technique to allow simultaneous measurements of compressive and shear properties using a combined compression/shear wave transducer