This study aimed to estimate the effects of environmental pollutants on the increase of hospitalizations due to cardiovascular diseases. This was an ecological study conducted in the city of São José do Rio Preto, São Paulo, Brazil, with data from hospital admissions with diagnoses in the categories of I-00 to I-99, from October, 1, 2011, to September 30, 2012. Fineparticulate matter (PM2,5), ozone, carbon monoxide, nitrogen oxide and nitrogen dioxide were the pollutants studied; they were estimated by CATT-BRAMs model. The use of an additive Poisson regression model showed association between exposure to PM2,5 and hospital admission due to cardiovascular diseases. In the fifth day after exposure to this pollutant (lag 5), the relative risk for hospitalization due to cardiovascular diseases increased 15 percent in according to 10 µg/m3 increase on PM2,5 concentrations. There were 650 avoidable hospital admissions and an excess of R$ 1.9 million in hospital expenses. Thus, it was possible to identify the association between exposure to PM2,5 and hospital admission due cardiovascular diseases in medium-sized cities, like São José do Rio Preto.