It is of great interest to planetary science to understand how the current experimental uncertainty on the hydrogen EOS affects the inferred structure of Jupiter. In particular, the mass of a core of heavy elements (other than H and He) and the total amount and distribution of heavy elements are very sensitive to the EOS of hydrogen and constitute important clues to its formation process. We present a study of the range of structures allowed by the current uncertainty in the hydrogen EOS. We show that an improved experimental understanding of hydrogen at Mbar pressures is necessary to put firm limits on the internal structure of Jupiter. © 2004 American Institute of Physics