The aim of this report was to determine Chagas infection incidence in pregnant women and congenital infection of their children in a hospital of a non-endemic area. From January 1990 to February 1991 we studied: a) 729 pregnant women with the serologic techniques of indirect hemagglutination and indirect immunofluorescence; b) 38 newborns from the 62 babies of seroreactive mothers with the parasitologic microhematocrit method to diagnose the infection. The serological tests were used as an index of the transplacental passage and for the eventual post-treatment control. We found 8.5% of women with Chagas disease, most of whom were born in an endemic area and did not know that they were infected (Table 1). We detected parasitemia in two newborns which represent 5.3% of congenital infection. Both babies were born in good conditions: at term, with normal weight and asymptomatic (Table 2). They were treated with nifurtimox and they showed a good response; the microhematocrit technique became negative a month later. At the end of the treatment the children were in perfect conditions showing an important decrease in the specific antibodies titer (Fig. 1). One of the cases was studied longer than the sixth month of life, maintaining negative serology. Our results in pregnant women are not different from those previously published in Buenos Aires; this points out the need to keep fighting the vector so as to lessen the existing reservoirs. We found a greater incidence of congenital Chagas disease with the microhematocrit technique than that previously published in Buenos Aires with other methods.(ABSTRACT TRUNCATED AT 250 WORDS)