Lumbar radicular pain is a fairly common health problem, yet its risk factors are far from clear. There are no published systematic reviews on associations between cardiovascular or lifestyle risk factors and lumbar radicular pain or sciatica. The aim of this systematic literature review was to assess associations between these risk factors and lumbar radicular pain or sciatica. We conducted a systematic search of the Medline database for all original articles on lumbar radicular pain or sciatica published until August 2006. Twenty-two papers from 19 studies were included in the review. Overweight or obesity was associated with sciatica in most of the case-control and cohort studies. Some studies showed an increased risk of lumbar radicular pain in smokers with a long smoking history or in those with high levels of physical activity. A few case-control studies showed an association between serum C-reactive protein and sciatica. No consistent associations were found for serum lipids levels or high blood pressure. In summary, the associations of overweight, long smoking history, high physical activity and a high serum C-reactive protein level with lumbar radicular pain or sciatica were substantiated by the present review. However, more prospective studies are needed in order to further clarify these associations and the mechanisms of action.