  We perform ab initio QED calculations of energy levels for the $n=1$ and
$n=2$ states of He-like ions with the nuclear charge in the range $Z = 12$-100.
The complete set of two-electron QED corrections is evaluated to all orders in
the parameter $\aZ$. Uncalculated contributions to energy levels come through
orders $\alpha^3 (\aZ)^2$, $\alpha^2 (\aZ)^7$, and higher. The calculation
presented is the first treatment for excited states of He-like ions complete
through order $\alpha^2 (\aZ)^4$. A significant improvement in accuracy of
theoretical predictions is achieved, especially in the high-$Z$ region.
