Congestive heart failure (CHF) induces a state of immune activation, and peritoneal macrophages (Ms) may play an important role in the development and progression of one such conditions. Moderate endurance training modulates peritoneal Mfunction. We evaluated the effect of endurance training on different stages of the phagocytic process and in the production of interleukin - 6 (IL-6), interleukin (IL-1) and tumor necrosis factor - a (TNF-) after lipopolisaccharide (LPS) stimulation. Either ligation of the left coronary artery or Sham operations were performed in adult Wistar rats. After 4 weeks, control (sham-operated) and MI (ligation of the left coronary artery) animals were randomly assigned to either a sedentary (Sham-operated sedentary, n=7 and MI sedentary, n=10) or a trained group (Sham-operated trained, n=8 and MI trained, n=8). Trained rats ran on a treadmill (0% grade at 13-20 m/min) for 60 min/day, 5 days / week, for 8-10 weeks, whereas sedentary rats had only limited activity. Training increased V0_2max normalized for body weight (ml kg^-1 min ^-1), as well as skeletal muscle citrate synthase maximal activity when compared with sedentary groups. The resident and total cell number, the chemotaxis index and TNF- production stimulated by (LPS) were significantly higher in the MI-sedentary group, when compared with the Sham-sedentary group. Moderate endurance training reversed these alterations promoted by post-MI. These results demonstrate that moderate intensity exercise training modulates peritoneal M function and induces beneficial metabolic effects in rats with post-MI CHF.