This incident case-referent study was conducted at Harare Maternity Hospital in 1989–1990 on 104 consecutive cases of stillbirth with unknown aetiology and 96 age- and parity-matched referents. Information was collected by interviewing the women following a standardized form and by review of antenatal cards. None of the women refused to participate. The most significant obstetric risk factors were prevalence of earlier stillbirths (odds ratio, OR = 6.1) and miscarriages (OR = 4.8). Low height and body mass index also increased the risk of having a stillborn baby significantly as well as a history of flue-like illness during pregnancy (OR = 4.6). The latter may have stimulated the women to book early causing the unexpectedly high OR for early booking among these cases. The pattern for the socio-economic risk factors was not easy to interpret. The most striking finding was the U-shaped relationship between socio-economic status and stillbirths with a higher risk among those with low and high statu