The association between risk factors for ischemic heart disease and plasma fibrinogen level was analyzed in a cross-sectional population study. All 51-year-old men living in a certain area within the county of Copenhagen were invited; 439 of 542 (81%) participated in the study. Data were collected via questionnaire and at health examinations. The following independent variables were analyzed: social variables, which included social class, marital status, and job strain; psychological and psychosomatic variables, which included abdominal pain, personal and economic problems, self-assessed state of health, and degree of loneliness; behavioral variables, which included smoking, drug consumption, physical activity, use of sugar, and alcohol consumption; and physiological variables, which included high density lipoprotein (HDL) and low density lipoprotein (LDL) cholesterol, physical fitness, fasting glucose level, waist-to-hip ratio, and systolic blood pressure. In the multivariate analyses, the following variables showed an independent positive association with plasma fibrinogen level: one social variable (low social class); two psychological variables (abdominal pain index and personal/economic problems); two behavioral variables (smoking and physical inactivity during leisure time); and three physiological variables (low HDL cholesterol, low physical fitness, and high LDL cholesterol). The strongest independent associations with plasma fibrinogen level were found for smoking, social class, LDL cholesterol, and HDL cholesterol. These analyses suggest that smoking is a major risk factor for an elevated plasma fibrinogen level, but that other factors such as social class, cholesterol level, physical inactivity/physical fitness, and psychological problems also influence plasma fibrinogen level.