High percentages of the yearly total precipitation concentration in a few very rainy days can increase the potential of erosion, slope instability and risks of floods, these problems are common in Peru. So it is important to know about the daily precipitation. In this paper, an investigation of the spatial and temporal patterns of daily precipitation concentration, in central Andes of Perú, by Concentration index (CI) that evaluates the varying weight of daily precipitation, the contribution of the days of greatest rainfall to the total amount, is presented. The index is applied to exponential curves such as Y = aX exp(bX), which adjust the accumulated percentages of precipitation Y contributed by the accumulated percentage of days X on which it took place, in the period 1964-2004, with which it is possible to generate concentration surfaces daily pluviometric. The highest concentration...