OBJECTIVE The aim of this study was to determine by a prospective study: the presence of anti-hepatitis E virus (HEV) and or HEV RNA in the colostrum of HEV infected mothers; transmission of HEV to infants from their mothers by breast-feeding. METHODS Ninety-three infected pregnant mothers in the third trimester of pregnancy of which 36 were positive for anti-HEV antibodies and 57 for HEV RNA (index patients) and 90 healthy pregnant mothers (control subjects) were studied. Maternal blood was taken at 7th and 9th of gestation and also within 5 days post-partum, along with colostrum and tested for anti-HEV and HEV RNA. Blood samples were collected from all infants at birth (cord blood) and at 1, 3, and 6 and 9 months of age. RESULTS There were 12 cesarean sections and eighty full term vaginal deliveries. Anti-HEV antibody and HEV-RNA was present in the colostral samples but in significantly lower levels ( p<0.001) as compared to corresponding maternal levels. Within 2 weeks post-partum, 6 of these 93 index patients, whose infants were anti-HEV antibody and HEV RNA negative at birth, developed acute hepatic disease. These mothers, four of whom delivered by cesarean section, had anti-HEV titers ranging from 1:10,000 to 1:60,000 and HEV RNA ranging from 1.5x10(6) to 2.5x10(4) copies/ml. Due to acute maternal disease their six respective infants were formula fed. Four of these infants were in close maternal contact, frequently kissed and cuddled, and developed symptomatic liver disease by 6-8 weeks of age. Apart from these 6 infants the remaining were exclusively breast-fed for 3.6+/-0.32 months. There was no evidence of HEV infection in the remaining babies. All mother-infant pairs from the control group remained anti-HEV negative throughout this study. CONCLUSIONS Although anti-HEV antibody and HEV-RNA are present in the colostrum of HEV infected mothers, breast-feeding appears to be safe for these infants. However this report must be confirmed by others. Transmission of infection may occur postpartum, through close contact of mother-infant pairs, especially in the presence of acute maternal disease.