Objectives: To evaluate the effect of vitamin A supplementation 24 h after delivery on breastmilk retinol concentration. Methods: Fifty low income women were randomly assigned to a single oral dose of 209 μmol of Vitamin A or none at delivery. Maternal serum and breastmilk retinol levels and infant morbidity and anthropometry were serially assessed. Results: Mean (95% CI) serum retinol levels increased in the supplemented mothers at 2.77 (2.3, 3.2) compared to 1.15 (0.9, 1.4) μmol/l in controls (P<0.05) and remained at a significantly higher level of 1.59 (1.4, 1.8) μmul/l compared to 1.33 (1.8, 1.5) μmol/l in the control group (P<0.001) up to a period of three months. Breastmilk retinol concentration was also greater at 24 h after supplementation, mean (CI) 11.34 (9.0, 13.7) μmol/l, compared to 2.95 (2.3, 3.6) μmol/l in the control group (P<0.0001), and remained higher for the next six months at 1.06 (0.9, ,1.3) μmol/l compared to 0.73 (0.6, 0.8) μmol/l in the control group (P<0.02). Infants of the supplemented mothers had reduced mean duration of respiratory tract infection of 3.1 (2.7, 3.5) days compared to 3.7 (3.3, 4.2) days (P<0.03) and mean incidence of febrile illness 0.1 (0.1, 0.1) compared to control infants 0.3 (0.3, 0.3) days, (P<0.002). Conclusion: Vitamin A supplementation of malnourished mothers maintains higher breastmilk retinol concentration for at least six months and reduces the duration of respiratory tract infection and febrile illness in their breastfed infants. Sponsorship: The study was supported by the International Centre for Diarrhoeal Disease Research and the United States Agency for International Development.