Duration of breastfeeding was studied in 556 women delivering at 2 maternity hospitals in Perth, Australia. At discharge 83.8% of women were breastfeeding their infants, including 6% who were giving complementary feeds. At 3 and 6 months, 61.8% and 49.9%, respectively, were still breastfeeding. In a Cox survival analysis of factors associated with duration of breastfeeding a positive association was found with maternal education, age and intended duration of breastfeeding. Male infants were more likely to be weaned before female infants and women whose partners were unemployed, or did not have a preference for breastfeeding, breastfed for shorter duration. There is still a need for programmes which support and encourage breastfeeding, focusing particularly on younger, less well-educated women who intend to breastfeed for less than the recommended 4-6 months.