  We consider a 2D isotropic Fermi liquid with attraction in both $s$ and $d$
channels and examine the possibility of a superconducting state with mixed $s$
and $d$ symmetry of the gap function. We show that both in the weak coupling
limit and at strong coupling, a mixed $s+id$ symmetry state is realized in a
certain range of interaction. Phase transitions between the mixed and the pure
symmetry states are second order. We also show that there is no stable mixed
$s+d$ symmetry state at any coupling.
