Infection is a potentially preventable cause of perinatal mortality but there is only limited epidemiological information on which to develop prophylactic guidelines. The aim of this study was to determine the population incidence of perinatal death from maternally acquired infection and to describe the responsible organisms and antibiotic sensitivities, and also the associated risk factors. Fetal and neonatal deaths from perinatal infection in the former Northern Health Region, United Kingdom, were identified for the years 1981-96 using data held by the Perinatal Mortality Survey, and the obstetric, paediatric and pathology case notes were reviewed. Maternally acquired bacterial infection of the baby was identified as responsible for 60 pre-delivery deaths and 142 post-delivery deaths among babies of 24 or more weeks gestation at birth between 1981 and 1996. There were 630,206 livebirths and 3,591 registered stillbirths in the survey area during this time. Bacterial infection was also considered the primary cause of death in 64 fetuses where delivery occurred at 20-23 weeks gestation between 1989 and 1996. Although group B streptococcus was the commonest single organism it was only responsible for 30% of all infectious deaths from 24 weeks gestation onwards. Ampicillin resistance was more common in the second half of the study. Infection remains an important cause of perinatal mortality but responsible organisms and antibiotic sensitivities have changed significantly over time. Although 80% of the post-delivery deaths would have received intrapartum antibiotics if current guidelines had been in place, the choice of antibiotics and identification of risk groups requires careful consideration.