  The result for the Higgs-dependent electroweak two-loop bosonic contributions
to the effective leptonic mixing angle of the $Z$-boson in the Standard Model
is presented. Together with the previously calculated fermionic contributions
it yields the complete dependence of $\sin^2\theta_{\rm eff}$ on the
Higgs-boson mass $M_H$. Compared to the fermionic contributions, the bosonic
contributions are found to be smaller and have the opposite sign, compensating
part of the fermionic contributions.
