ABSTRACT: Background: Depression after the birth of a baby is a common cause of maternal morbidity, and its prevalence in Australia is 10 to 15 percent at 6 to 9 months postpartum. This study assesses the prediction of postnatal depression at 6 weeks postpartum, Method: Women at 24 weeks' gestation or less were invited to complete a Modified Antenatal Screening Questionnaire (MASQ) that identified women more vulnerable to becoming depressed after childbirth. Of these 249 women, 144 (58%) screened more vulnerable, and were randomly allocated to receive either a supportive intervention to reduce postnatal depression or to receive no intervention. At 6 weeks postpartum the women completed the Edinburgh Postnatal Depression Scale (EPDS) to assess their mood after the birth. Results: No difference occurred at 6 weeks postpartum between the MASQ vulneruble group (return rate 64/68) and the MASQ less vulnerable group (return rate 44/51) in the frequency of those who screened as potential candidates for major depression using the EPDS. For major depression the MASQ's sensitivity was 73 percent, specificity 43 percent, positive predictive value 17 percent, and negative predictive value 91 percent; for minor depression its sensitivity was 81, 48, 34, and 89 percent, respectively. The MASQ was able to predict minor depression. More women in the vulnerable group scored at increased risk of minor depression on the EPDS at 6 weeks postpartum. Conclusion: Further studies are needed to extend this work and develop a screening test with higher specificity and greater positive predictive value.