  The zero-point energy of a massless fermion field in the interior of two
parallel plates in a D-dimensional space-time at zero temperature is
calculated. In order to regularize the model, a mix between dimensional and
zeta-function regularization procedure is used and it is found that the
regularized zero-point energy density is finite for any number of space-time
dimensions. We present a general expression for the Casimir energy for the
fermionic field in such a situation.
