As evidence accumulates to implicate fibrinogen as a risk factor for cardiovascular disease (CVD) it becomes important to characterize the levels and correlates of fibrinogen in diverse populations. Knowledge of the correlates of fibrinogen may help researchers to disentangle the independent contribution of elevated fibrinogen concentrations to CVD. Characterization of the normal range and possible determinants of fibrinogen concentrations, likewise, may aid CVD risk assessment and intervention research. Fibrinogen concentrations vary widely among populations and increase with age. Levels are consistently higher in women than men and rise after menopause. Smoking is the most important lifestyle correlate of fibrinogen. People with diabetes and hypertension have elevated fibrinogen levels, as do sedentary and obese individuals. Alcohol intake and oestrogen replacement therapy are associated with lower fibrinogen levels. Most other CVD risk factors are correlated positively with fibrinogen. Fibrinogen is clearly a marker of CVD risk. Yet, the strikingly non-specific pattern of higher fibrinogen with every CVD risk factor suggests that proving an independent causal role of fibrinogen will remain elusive in the absence of trials selectively lowering fibrinogen with the aim of reducing CVD.