  We investigate the concept of superconformal symmetry in six dimensions,
applied to the interacting theory of (2,0) tensor multiplets and self-dual
strings. The action of a superconformal transformation on the superspace
coordinates is found, both from a six-dimensional perspective and by using a
superspace with eight bosonic and four fermionic dimensions. The transformation
laws for all fields in the theory are derived, as well as general expressions
for the transformation of on-shell superfields. Superconformal invariance is
shown for the interaction of a self-dual string with a background consisting of
on-shell tensor multiplet fields, and we also find an interesting relationship
between the requirements of superconformal invariance and those of a local
fermionic kappa-symmetry. Finally, we try to construct a superspace analogue of
the Poincare dual to the string world-sheet and consider its properties under
superconformal transformations.
