The aim of the study was to document the role of laboratory investigations for unexpected stillbirths at term. It was a retrospective casenote review of 75 unexpected stillbirths at term from 1995 to 1999, at the National Maternity Hospital, Dublin, Republic of Ireland. Investigations performed included blood tests, chromosomal analysis, autopsy and placental histology. Perinatal autopsy was the most informative investigation with positive findings in 49% of cases. There were positive placental findings in 37% of cases. Six of the 26 cases showed abnormal karyotyping. Of the blood tests performed, the Kleihauer-Betke test was most informative, revealing a feto-maternal haemorrhage in 8% of cases and anticardiolipin antibodies were positive in 4% of cases. FBC, TORCH and glycosylated Hb were negative in all 75 patients. Despite thorough investigations 32 of cases (43%) remained unexplained.