  The systematic investigation of hyperdeformation (HD) at high spin in the
$Z=40-58$ part of the nuclear chart has been performed in the framework of the
cranked relativistic mean field theory. The properties of the moments of
inertia of the HD bands, the role of the single-particle and necking degrees of
freedom at HD, the spins at which the HD bands become yrast, the possibility to
observe discrete HD bands etc. are discussed in detail.
