This paper summarizes the research efforts conducted in Mexico to develop seismic guidelines for the design of base-isolated structures. The proposed guidelines are based on the seismic provisions of Mexican seismic codes and their philosophy, but include several recommendations available for base-isolated structures in the UBC-97 and IBC-2000 seismic codes of the United States. Additional requirements were added to account for regional seismicity. Finally, new provisions were derived from original research on the torsional response for base-isolated structures and orthogonal effects, among other topics.