Circulating inflammatory markers [plasma fibrinogen, viscosity and C-reactive protein (CRP)] have been associated with cardiovascular risk factors. In part, these associations may reflect 'upstream' changes in pro-inflammatory cytokines - interleukin (IL)-6, IL-18 and tumour necrosis factor (TNF)alpha. These variables were measured in 1666 men and women aged 25-64 years and their associations with risk factors were studied. All six markers increased significantly with age. IL-18 and TNFalpha levels were higher, and fibrinogen levels lower, in males. Oral contraceptive use increased levels of CRP, whilst postmenopausal women had elevated IL-18 levels. Inflammatory markers were also associated with components of the metabolic syndrome. Most inflammatory markers showed an increasing trend with alcohol consumption in men and a decreasing trend in women, and increasing trends with level of smoking. Inflammatory markers generally showed strong positive associations with social deprivation. After adjustment for classical risk factors, IL-6, IL-18 and TNFalpha retained significant associations with social deprivation only in men (P < 0.008). We conclude that pro-inflammatory cytokines are associated with several cardiovascular risk factors including social deprivation, and may mediate some of their associations with 'downstream' inflammatory markers (fibrinogen, viscosity and CRP).