Soil erosion is a process caused by several factors, including precipitation. Causing the water erosive process, through the detachment and transport by surface runoff of soil particles.This phenomenon depends on the intensity, frequency and duration of eventsin a given region. Thus, the objective was to determine the rainfall erosivity indices through rainfall data. The period of rainfall data used was between the years 1943 to 1985, for the municipality of Piaçabuçu, located in the lower São Francisco Alagoano region. These data were tabulated to calculate rainfall, rainfall coefficient and its relation to erosivity using six equations. The municipality of Piaçabuçu has an average annual rainfall distribution of 1128.52 mm for the observation period of 42 years, with a wide variation in the distribution of rainfall over the years, with the rainy season concentrated in the months of March to August , presenting average values above the average, in this period it precipitated more than 70% of the rains for the municipality.Todos os seis modelos de estimativas da erosividade apresentaram correlação considerada alta, o que os capacita para a estimativa da erosividade do município em estudo.All six erosivity estimation models presented a high correlation, which enables them to estimate the erosivity of the municipality under study.