Relativistic covariance of quasipotential equations

We argue that many of the relativistic three-dimensional (quasipotential) equations used in hadron physics are inconsistent with the discrete symmetries like charge conjugation and CPT, yielding an incorrect Lorentz structure for the calculated Greenʹs functions. As an exception to this we consider the equal time approximation to the Bethe-Salpeter equation. We also present a covariant quasipotential model for the pion-nucleon interaction based on hadronic degrees of freedom.