  I find the three-loop contribution to the effective potential for the
Standard Model Higgs field, in the approximation that the strong and top Yukawa
couplings are large compared to all other couplings, using dimensional
regularization with modified minimal subtraction. Checks follow from gauge
invariance and renormalization group invariance. I also briefly comment on the
special problems posed by Goldstone boson contributions to the effective
potential, and on the numerical impact of the result on the relations between
the Higgs vacuum expectation value, mass, and self-interaction coupling.
