Four generations, Higgs physics, and the MSSM

We consider the effects of a fourth generation of chiral fermions within the MSSM (minimal supersymmetric standard model). Such a model offers the possibility of having the lightest neutral Higgs boson significantly heavier than in the three generation MSSM. The model is highly constrained by precision electroweak data, along with Higgs searches at the Tevatron. In addition, the requirements of perturbative unitarity and direct searches for heavy quarks imply that the four generation MSSM is only consistent for tan{beta}{approx}1 and highly tuned 4th generation fermion masses.