Monthly prevalence of canine rabies in Argentina (1971-1993), Bolivia (1987-1993) and Paraguay (1976-1993) were analyzed to identify seasonal cycles of the disease. Moreover, data to forecast the evolution of rabies were studied. The time series analysis was employed. This included the Fourier Harmonie Analysis and Box-Jenkins ARIMA-SARIMA multiplicative models. Cycles were detected in Argentina and Paraguay. The seasonal cycles occurred at the end of winter and spring. Seasonal cycles were about every four years, and the next peak was estimated for 1997.