Abstract: Head-space GC determination of methyl methacrylate (MMA) released from bone cement was proposed and conditions of head-space,including time and temperature for equilibrium,were studied and optimized.Standard curve in the mass concentration range of 0.3-15.0 mg·L-1 was prepared with addition of 1.05 mg·L-1 of ethylacetate as internal standard to improve precision of the determination.Linearity was attained in the concentration range tested.Detection limit (3S/N) of the method found was 94.5 μg·L-1.Test for recovery was made by addition of 1.05 mg·L-1 of standard MMA for 5 determinations,values of recovery found were ranged from 97.6% to 101.8% with RSD′s (n=5) less than 2%.Equilibrium of release of MMA was attained after 20 min in the simulated condition of orthopaedic operation.