  We search for deviations from next-to-leading order QCD evolution in HERA
structure function data. We compare to data predictions for structure functions
in the small x region, obtained by evolving backwards to low Q^2 the results of
a parton fit performed in the large Q^2 region, where fixed-order perturbative
QCD is certainly reliable. We find evidence for deviations which are
qualitatively consistent with the behaviour predicted by small x perturbative
resummation, and possibly also by nonlinear evolution effects, but incompatible
with next-to-next-to leading order corrections.
