One hundred milk or colostrum samples from 78 mothers with chronic Chagas' disease were parasitologically studied for Trypanosoma cruzi infection by means of direct examination and inoculation of mice. The mice were sumbitted to direct blood examination three times a week. At the end of 45 days, xenodiagnosis and indirect immunofluorescent test (IFAT) for T. cruzi antibodies werw carried out in animals. No parasitized sample was observed even through five mothers had parasitemia at milk collection. In addition, 97 breast-fed children of chronic chagasic mothers, born free of infection, were tested for IgG antibodies to T. cruzi using IFAT. No case of T. cruzi infection was detected. The authors conclude that breast-feeding should not be avoided for children of chronic chagasic women. However, as these mothers had intermitente parasitemia, they should avoid nursing when there is nipple bleeding