We investigated the use of the focused ion-beam (FIB) technique as a nanofabrication tool for the implementation of oxide-based magnetic and magnetoelectronic functional devices. In particular, we studied the effect of using FIB lithography for the patterning of La(2/3)Ca(1/3)MnO(3) magnetic oxide thin films. Results obtained show that the transport properties of patterned areas were strongly degraded after the patterning process. In contrast, no degradation was detected when the patterning was performed using a less aggressive technique. The origin of this degradation correlates with Ga(+) ion implantation, as indicated by Auger spectroscopy analysis of the patterned films.