Objective: To establish whether the scavenging effect reduces the PM2.5/PM10 ratio in rainy periods in comparison with dry periods, at the Kennedy locality of Bogotá, Colombia. Materials and methods: Relationships among hourly and daily PM10, PM2.5, PM2.5/ PM10 ratio, temperature, relative humidity and precipitation records from the Kennedy air quality station from January 2007 to September 2011 were analyzed. Results: The hourly mean PM2.5/PM10 ratio was 0.36 (SD= ± 0.12), with an hourly maximum of 0.96. In rainy hours, the PM2.5/PM10 ratio was 0.41 (SD= ± 0.13) and was reduced to 0.36 (DE= ± 0.12) in dry hours. On the other hand, the daily mean PM2.5/PM10 ratio was 0.36 (SD= ± 0.09) with a daily maximum of 0.79. The daily mean on rainy days was higher (0.39; SD= ± 0.09) than that recorded on dry days (0.34; SD= ±0.08). All these differences were statistically signifi cant. Conclusions: Precipitation reduces PM2.5 concentrations at a lower extent than it reduces PM10 concentrations. The analysis was not conclusive about the effect of precipitation on PM2.5 concentrations, so it is not possible to assert that precipitation reduces the risk associated with the exposure to airborne particulate matter. To deepen our knowledge about the effect of precipitation on particulate matter pollution, it is recommended to apply additional techniques such as particle counting and particulate matter chemical characterization.