  We show numerically that correlation length at the critical point in the
five-dimensional Ising model varies with system size L as L^{5/4}, rather than
proportional to L as in standard finite size scaling (FSS) theory. Our results
confirm a hypothesis that FSS expressions in dimension d greater than the upper
critical dimension of 4 should have L replaced by L^{d/4} for cubic samples
with periodic boundary conditions. We also investigate numerically the
logarithmic corrections to FSS in d = 4.
