We consider the integral functional
integral f(x, Du) dx
under non-standard growth assumptions that we call p(x) type: namely, we as
sume that
\z\(p(x)) less than or equal to f (x, z) less than or equal to L (1 + \z\(p
(x))),
a relevant model case being the functional
integral \Du\(p(x)) dx.
Under sharp assumptions on the continuous function p(x) > 1 we prove regula
rity of minimizers. Energies exhibiting this growth appear in several model
s from mathematical physics.