Introduction: Epidemiological studies conducted in Latin America and the Caribbean (LAC) related to air pollution and mortality have reported results exclusively in countries like Brazil, Chile and Mexico, which have seasonal cycles and do not assess the precipitation variable in its design. The topography and latitude conditions, make the results of LAC cannot be generalized, reason why this study evaluated the modifying effect of precipitation in the relationship with acute exposure to PM10 and mortality from all causes and cardiopulmonary causes, in the city of Bogotá, Colombia. Methods: A time-series ecological study was conducted from 1998 to 2006. It was stratified by dry and rainy day, based on daily accumulated rainfall in different areas of the city. In order to model the relationship between the daily numbers of deaths, with levels of PM10, the Generalized Additive Models with Poisson response were used. Simple lag models were adjusted on the day of the event (lag0) to calculate the percentage change in risk of mor¬tality for a 10μg/m3 increase in PM10 levels, evaluating the modifying effect of precipitation and adjusting for potential confounders. Results: For all ages, the percentage change in risk of mortality from all causes in rainy days was 0.41% (CI 95%:0.01%, 0.81%) and in dry days was 0.33% (CI 95%:-0.13%, 0.81%), per 10μg/m3 increment in daily average PM10 in the day of the event (lag0). For all ages, the percentage change in risk of mortality from respiratory causes in rainy days was 1.04% (CI 95%:0.05%, 2.04%) and in dry days was 0.47% (CI 95%:-0.64%, 1.59%), per 10μg/m3 increment in daily average PM10 in the day of the event (lag0). Conclusions: The results suggest a statistically significant modifying effect of precipitation scavenging in relation with mortality for all causes and respiratory causes and acute exposure to PM10 in Bogotá.