  We consider gauge coupling unification in models with TeV scale strings and
large compact dimensions realized as type IIB string orientifolds. Following an
observation by Ibanez we show that the gauge couplings at low energies can
behave as if they effectively unify at $M_U \sim 2 \times 10^{16} GeV$ with
$\alpha_U \sim 1/24$. This requires the $\sigma$ model anomaly coefficients
$b_a^{i'}$ not to be all equal and their ratio to the $\beta$-functions of
minimally supersymmetric Standard Model $\beta_a$ to be a constant independent
of the gauge group. If, in addition, $b_a^{i'}$ have a gauge group independent
constant piece the relation between the unified gauge coupling and the dilaton
VEV is modified so that there can be weakly coupled gauge theories arising from
strongly coupled strings.
