BACKGROUND: The emergency contraceptive pill (ECP) has the potential to assist in reducing unintended pregnancy and abortion rates. Since its rescheduling to pharmacy availability without prescription in Australia in January 2004, there is little information about Australian women's knowledge, attitudes and use of the ECP. The aim of this study was to measure the knowledge about the ECP and sociodemographic patterns of and barriers to use of the ECP. STUDY DESIGN: A cross-sectional study, using a computer-assisted telephone interview (CATI) survey conducted with a national random sample of 632 Australian women aged 16-35 years. RESULTS: Most women had heard of the ECP (95%) and 26% had used it. The majority of women agreed with pharmacy availability of the ECP (72%); however, only 48% were aware that it was available from pharmacies without a prescription. About a third (32%) believed the ECP to be an abortion pill. The most common reason for not using the ECP was that women did not think they were at risk of getting pregnant (57%). Logistic regression showed that women aged 20-29 years (OR 2.58; CI: 1.29-5.19) and 30-35 years (OR 3.16; CI: 1.47-6.80) were more likely to have used the ECP than those aged 16-19 years. Women with poor knowledge of the ECP were significantly less likely to have used it than those with very good knowledge (OR 0.28; CI: 0.09-0.77). Those in a de facto relationship (OR 2.21; CI: 1.27-3.85), in a relationship but not living with the partner (OR 2.46; 95% CI 1.31-4.63) or single women (OR 2.40; CI: 1.33-4.34) were more likely to have used the ECP than married women. CONCLUSIONS: Women in Australia have a high level of awareness of the ECP, but more information and education about how to use it and where to obtain it are still needed.