  Natural wormholes and its astrophysical signatures have been sugested in
various oportunities. By applying the strong field limit of gravitational
lensing theory, we calculate the deflection angle and magnification curves
produced by Morris-Thorne wormholes in asimptotically flat space-times. The
results show that wormholes act like convergent lenses. Therefore, we show that
it is hard to distinguish them from black holes using the deflection's angle of
the gravitational lens effect, in contrast with the results reported by Cramer
et.al. and Safanova et.al. However, we also show that it is possible, in
principle, distinguish them by the magnification curves, in particular, by
observing the position of the peak of the Einstein's ring.
