  We study the heavy Higgs sector of the MSSM composed of the H^\pm, H^0 and
A^0 particles in the so-called decoupling limit where m_{A^0} >> m_Z. By
integrating out these heavy Higgs particles to one-loop, we compute the
effective action for the electroweak gauge bosons and find out that, in the
decoupling limit, all the heavy Higgs effects can be absorbed into
redefinitions of the Standard Model electroweak parameters. This demonstrates
explicitely that the decoupling theorem works for the heavy MSSM Higgs
particles. This is also compared with the paradigmatic and different case of
the Standard Model heavy Higgs particle. Finally, this work together with our
two previous works, complete the demonstration that all the non-standard
particles in the MSSM, namely, squarks, sleptons, charginos, neutralinos and
the heavy Higgs particles, decouple to one-loop from the low energy electroweak
gauge boson physics.
