We analyzed parental death from stroke and other potential risk factors in relation to the incidence of stroke among 789 men, all 54 years old at the base-line examination. During 18.5 years of follow-up, 57 men (7.2 percent) had strokes. In univariate analyses, the following characteristics correlated significantly with the incidence of stroke: increased systolic (P = 0.004) and diastolic blood pressure (P = 0.0001), larger waist circumference (P = 0.007), higher waist:hip ratio (P = 0.0004), increased plasma fibrinogen level (P = 0.01), and lower vital capacity (P = 0.03). In addition, men whose mothers had died of stroke had a threefold increase in their incidence of stroke as compared with men without such a maternal history (P = 0.0005). Potential risk factors for stroke that were not confirmed were body-mass index, serum cholesterol level, hematocrit, blood glucose level, smoking, coronary heart disease, electrocardiographic signs of left ventricular hypertrophy, and a paternal history of death from stroke. In multivariate analyses, increased blood pressure, abdominal obesity, increased plasma fibrinogen level, and maternal history still correlated significantly with the risk of stroke. A maternal history of stroke should probably be added to the list of risk factors for stroke among middle-aged men.