The association between five socioeconomic indices (lifetime occupation, education, income, ownership of material possessions, and childhood socioeconomic status) and plasma fibrinogen levels was investigated in middle-aged Finnish men who were part of the Kuopio Ischemic Heart Disease Risk Factor Study. The Kuopio Ischemic Heart Disease Risk Factor Study is based on a representative age-stratified sample of 2,682 men aged 42, 48, 54, and 60 years. The data were collected between 1984 and 1989. The present analysis is restricted to the 2,011 men for whom information on fibrinogen and all covariates was available. The covariates were alcohol consumption, body mass index, physical fitness, smoking, coffee consumption, high density lipoprotein cholesterol, low density lipoprotein cholesterol, blood leukocyte count, and prevalent disease (at least one sign of ischemic heart disease, hypertension, diabetes, or previous stroke). An age-adjusted inverse association was found between levels of plasma fibrinogen and four of the five socioeconomic indices: current income, education, lifetime occupation status, and current material possessions. After adjustment for the covariates, the association persisted for education, current income, and lifetime occupation. Analysis of the joint effect of childhood and adult socioeconomic status indicated that those who were economically disadvantaged at both times had the highest fibrinogen levels, but the fibrinogen levels of those who were not poor as adults had no variation by childhood socioeconomic status.