A population-based case-control study of 416 histologically diagnosed, incident gliomas in adults was carried out in Melbourne, Australia, to determine whether past medical, family or reproductive histories are risk factors for developing glioma. A total of 422 controls were selected from the Australian electoral roll and matched to cases for age, sex and post code of residence. An increased risk of developing glioma was observed among first-born individuals OR (95% CI) 2.0 (1.4-2.9). It is possible that this effect is due to residual confounding by socio-economic status or that it is a chance finding. Alternatively, it may be that this is due to some other effect linked to the first pregnancy, such as maternal age, birth weight or circumstances of delivery. There was no apparent association between the development of glioma and other neuropsychiatric or general medical conditions or with family history or reproductive history. Allergies (asthma and eczema) were not associated with a decreased risk of glioma, as has previously been suggested.