Effects of scalar mixing in ${g}{g} \rightarrow \mbox{Higgs} \rightarrow \ga\ga$

We discuss the effects of mixing of scalars belonging to left-- and right--chiral MSSM super--multiplets on the process ${g}{g}\rightarrow \hnl \rightarrow \ga\ga$, which is a promising channel for the discovery of the lightest CP--even MSSM Higgs boson at the LHC and the SSC. The effects of the left--right scalar mixing are small in most of parameter space. However, there exist regions where the mixing is important. Due to mixing, there can be large enhancements of the cross section in a region of parameter space where the no--mixing approximation yields a value that is too low for experimental discovery of the $\hnl$ at the LHC and the SSC.