We have investigated the relationship between extreme anomalies in the monthly precipitation of the Pampa Region (PR), Argentina, and large-scale circulation anomalies over the South American continent and the neighboring oceans. The composite maps of the extreme rainfall anomalies reveal that this atypical behavior extends beyond the PR and that comparable anomalies simultaneously take place in the center and south of Chile and in the western South Atlantic Ocean. We have analyzed the anomalies in the water vapor flux and in the circulation of the lower and upper levels of the troposphere that occurred in 85 months with extreme rainfall anomalies between 1955 and 1998. The study combines the use of a complete set of observed precipitation data and several atmospheric variables from the National Centers for Environmental Prediction Reanalysis. We have found well-defined anomalous circulation patterns that embrace the south of the continent and the vicinity of the Pacific and Atlantic Oceans, which are very similar but of opposite signs for both rainfall extremes. The interaction between these anomalies in the high-level flow and the subtropical jet stream generates the necessary conditions for vorticity advection and flow divergence, which is consistent with the expected vertical motions. The principal component analysis was applied to the pressure anomaly fields to distinguish those aspects of the large-scale patterns that are more directly related with the rainfall extremes. The amplitudes of some of the dominant PC are significantly correlated with the precipitation anomalies, and they highlight the mechanisms leading to rainfall extremes during El Ni¿o-Southern Oscillation, and neutral periods.