Recently, seismic quiescence based on P.D.E. and I.S.C. data, has been reported in the Acapulco-San Marcos region (16¿--17.2¿ N, 98.5¿--99.7¿ W) (McNally, 1981). In order to assess the seismic potential of this region we have estimated seismic moments and slips associated with 1957 (Ms=7.5) and 1907 (Ms=8.0) events which occurred in this area. Historical data suggest that earthquakes occurred in the region in 1845 (Ms≂7.9) and probably also in 1820 (Ms≂7.6). We find preference for the time-predictable model in the data set which, if valid, forecasts the next large earthquake between now and 1993 with 1985 as the most likely year. Although this forecast can not be taken as definitive since it is based on several assumptions (each of which are reasonable but uncertain), the implications of reported quiescence and the results of this paper suggest a careful monitoring of the area.