Hydrological studies in the La Plata basin are important as it is a source capable of providing water to several countries in South America, a large navigable network and rich in mineral resources. However, the necessity of these studies is highlighted by the frequent floods that occur in it. In this work, it is proposed to employ the statistical modelling through the Seasonal Autoregressive Integrated Moving Average (SARIMA) models, with the aim to represent and forecast the time series for monthly streamflow in different stations in the La Plata Basin. Proper models were proposed for the monthly streamflow time series in Timbúes station (Paraná River) for five subtemporal periods of twenty years from 1913 to 2012. Moreover, for Corrientes, Timbúes and Paso de los Libres stations, a forecast for 32 months (January/2013-August/2015) was carried out taking into consideration the last subperiod, 1993-2012. The validation of the models was considered. Finally, forecast with different future scenarios were done in Corrientes station, and a comparison with the gauged values was included. In this way, it was pretended to find a statistical models in order to contribute to the monitoring of the monthly discharge in the La Plata Basin with the objective to mitigate negative impacts in the region