HIGH ENERGY ZEROS AND OTHER TYPES OF ZEROS IN PHOTOIONIZATION author L. A. LaJohn and R. H. Pratt Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA 15260, USA We discuss a class of zeros found at relativistic energies in photoionization matrix elements. They occur in dipole $(n,l,j) \rightarrow (\epsilon ,l+1,j)$ transitions, for energies greater than 100 keV, and they have observable physical consequences in photon electron polarization correlations $C_{i j}$, especially $C_{23}$. We describe properties of these zeroes and compare them with other classes of photoionization zeros.