Zero sets of real polynomials containing complex varieties

We give necessary conditions in terms of defining
function for real algebraic hypersurface (possibly with singularities)
to contain nontrivial germs of complex hypersurfaces.
This result is useful in view of {\sl the one side extension} phenomenom
due to Trepeau.
Moreover, if a real hypersurface $S$ in $\bold C^2$ is
defined by a real polynomial of a sufficiently general form and if $S$
contains a nontrivial analytic disk, then, using the abobe result, we
show that $S$ must contain certain complex lines.