The present study aimed to determine the incidence of primary postpartum haemorrhage (PPH) after vaginal birth at an Australian tertiary hospital, and to investigate risk factors for primary PPH at this hospital. A case-control study of women delivering vaginally at a tertiary hospital from February to June 2003 was performed. Demographic, antenatal, intrapartum, treatment and outcome data were abstracted from patient records. The study population comprised 125 cases and 125 controls, with a primary PPH rate of 12.1 per 100 vaginal births. Risk factors on multivariate analysis were past history of PPH, second stage labour > 60 min, forceps delivery, and incomplete placenta/ragged membranes.