Abstract. We consider non-autonomous semilinear elliptic equations of the typewhere Ω ⊂ R 2 is either a ball or an annulus centered at the origin, α > 0 and f : R → R is C 1,β on bounded sets of R. We address the question of estimating the Morse index m(u) of a sign changing radial solution u. We prove that m(u) ≥ 3 for every α > 0 and that m(u) ≥ α + 3 if α is even. If f is superlinear the previous estimates become m(u) ≥ n(u) + 2 and m(u) ≥ α+n(u)+2, respectively, where n(u) denotes the number of nodal sets of u, i.e. of connected components of {x ∈ Ω; u(x) = 0}. Consequently, every least energy nodal solution uα is not radially symmetric and m(uα) → +∞ as α → +∞ along the sequence of even exponents α.