On the hypothesis that the density changes inside the Earth, down to a depth of 5000 km., are essentially due to pressure and conform to the writer's compressibility-pressure Earth model, it is shown that, if Venus and the Earth are of the same primitive composition, it is more probable than not that Venus contains an inner core. This supports the evidence previously found (on the same hypothesis) from the case of Mars that the Earth's inner core is chemically distinct from the rest of the Earth. A formal relation between the rotation period and the ellipticity of Venus is derived and discussed.