METHODS:This is an ecological-social study that used the number of leprosy cases reported to the Brazilian Ministry of Health from January 2004 to December 2006. Monthly series were generated in each regional health department, and their sequences were adjusted by a Markovian model for the leprosy detection coeffi cients. The detection coeffi cient with the number of cases accumulated in the period in each municipality was used to produce the spatial distribution of the endemy; a correlation analysis was carried out with the leprosy detection coeffi cients and the components of the Social Responsibility Index of the state of São Paulo. RESULTS:Of the 645 municipalities of the state of São Paulo, 22 did not detect leprosy cases in the period. In the majority of regions, the endemy showed a decreasing trend; the time series presented random fl uctuation around expected values. The decline was infl uenced by a generalized decrease in the detection coeffi cients at the end of 2005. There was a positive correlation between the detection coeffi cients and the components "schooling" and "longevity", of the Social Responsibility Index of the state of São Paulo, and a negative correlation with "wealth", another component of the same Index. CONCLUSIONS:The result of the time series analysis suggests that the endemy is on the decline in the majority of regions of the state of São Paulo, while the spatial analysis shows that the coeffi cients are high in the northern part of the state.