The knowledge of high pressure densities and speeds of sound of biodiesel fuel is crucial for the optimization of diesel engines operation, namely, for the injection process, to achieve a complete combustion. However, the experimental data for these properties are still very sparse in the literature. This work reports the densities and speeds of sound measured at pressures from atmospheric to 200 MPa and temperatures from (293.15 to 393.15) K for two biodiesel fuels (soybean and rapeseed). The density data were measured only up to 100 MPa and later extrapolated for pressures up to 200 MPa by integration of speed of sound data. An equation of state was then proposed to describe both density and speed of sound within their estimated uncertainties and used to assess the density and its derivatives.