OBJECTIVE: To evaluate the effects of swimming on pulmonary water content in animals with heart failure (HF) after myocardial infarction (MI). METHODS: After coronary occlusion, MI size 20%<MI 40% of the LV large. The animals swam for 60 min/day, 5 days/week for 8 weeks. The wet weight of lung, liver, atriums, LV and right ventricle (RV) as well as the dry weight of the liver and lung were determined. ANOVA and Tukey test were used for statistical analysis. RESULTS: An increase in the atrium/body weight ratio was noted in the sedentary animals with moderate (MImod-SED: n=8) and large (MIlg-SED: n=10) infarctions in comparison to the sedentary control (C-SED: n=14) and trained (C-TR: n=16) rats. An increase in the RV/body weight and LV/body weight ratios was noted in the MIlg-SED. The heart/body weight ratio was higher in MIlg-SED when compared to the other groups. The infarcted trained animals presented diminished hypertrophy. The pulmonary water content was higher in MIlg-SED animals (81±0.4%) than in C-SED animals (79±0.4%). No differences were found for the other comparisons (C-TR: 79±0.4%; MImod-SED: 80±0.3%; MImod-TR: 80±0.6%; MIlg-TR: 79±0.7%). CONCLUSION: The increase of cardiac mass and pulmonary water content presented by MIlg-SED was diminished in the trained animals. The results suggest that the practice of physical exercise can diminish HF and contribute to favorable cardiac remodeling.