  The structure of the Higgs sector in the minimal supersymmetric standard
model is reviewed at the one-loop level. An on-shell renormalization scheme of
the MSSM Higgs sector is presented in detail together with the complete list of
formulae for the neutral Higgs masses at the one-loop level. The results of a
complete one- loop calculation for the mass spectrum of the neutral MSSM Higgs
bosons and the quality of simpler Born-like approximations are discussed for
sfermion and gaugino masses in the range of the electroweak scale.
