PURPOSE--Comparative analysis of cardiac weight (CW) in patients with chronic Chagas disease, with or without parasitism by Trypanosoma cruzi in the central vein of the adrenal gland (CVAG). METHODS--The CW has been studied in 96 necropsied individuals with chronic Chagas disease. Among them, 48 of them had Trypanosoma cruzi nests on the wall of the CVAG and the other 48 patients did not have nests in the CVAG. Later, this sample was paired for sex, age and anatomo-clinical form, resulting in 60 patients. Among these patients, 30 of them had Trypanosoma cruzi nests on the walls of the CVAG and the other 30 did not have. RESULTS--The CW of Chagas patients which had nests of T. cruzi in the CVAG, was 484.8 +/- 146.0g, while in the ones that did not have the nests on the walls of the CVAG, the CW weight was 415.8 +/- 125.3g. This difference was statistically significant. In the first group it had a prevail of congestive heart failure. Subsequently to the pairing for sex, age and anatomo-clinical form, the CW was respectively 464.3 +/- 146.2g and 436.0 +/- 108.9g. This difference was not statistically significant. CONCLUSION--These data suggest that the parasitism in the central vein of the adrenal gland, combined with other possible events intrinsic to the chronic Chagas disease patients' hearts, carries a supporting role in the increasing of the cardiac weight and in the congestive cardiac insufficiency.