The spatial patterns of rainfall over the Azul Riverbasin (Argentina) are examined for the period 1985-1994 (12 stations) and 1967-1994 (6 stations) using principal components analysis. Analyses are performed using monthly precipitation data. Most of the variance (around 89%) is explained by the first two components. On the basis of both analyses -no essential difference in pattern occurs between one period and the other- the watershed is divided into three coherent regions. In this aspect, each region can be considered to behave in a similar fashion.