Zinc, iron and copper content in serum of 75 myocardiopathic chagasic patients together with that in 29 healthy controls were determined. Blood samples were taken by catheterization from the superior cava vein, coronary sinus, pulmonary artery and a peripheral artery, usually the femoral. In general, serum zinc and iron levels tend to diminish in chagasic patients, while serum copper levels tend to increase. The coronary, systemic and peripheric gradients indicate that all these metal elements tend to deposit in heart tissue. Although zinc and iron tend to be deposited also in liver and other tissues, copper is released from them into the blood stream. Further studies should determine the requirement of these metal species in heart and other tissues of experimental animals in order to obtain more conclusive information about the cause of the serum metal impairment observed here.