The strength of electric monopole (E0) transitions is related to differences in mean-square charge radii and differences in quadrupole deformation in nuclei. Estimates are made of E0 decay versus M1, E1, and E2 decay out of superdeformed bands. It is suggested that E0 decay may dominate, providing a (partial) answer to the superdeformed band

drainingr problem.
Communicated by D. Schwalm