Possible risk indicators of ischemic heart disease relevant to the occupation of professional driving were identified in a cohort of 440 professional drivers and 1000 referents from the Swedish countries of Västerbotten and Norrbotten. The subjects were randomly selected. Data on cardiovascular risk indicators were collected from questionnaires, blood pressure measurements, serum lipid levels, height, and weight. The results showed that significantly more drivers than referents were overweight, smokers, and shift workers; were sedentary in their leisure time; and had a work situation characterized by high demands, low decision latitude, and low social support. There were no significant differences concerning blood pressure and serum lipid levels. The odds ratio for having a high score on a cardiovascular risk index was 3.18 (95% confidence interval 2.41-4.20) for the drivers when they were compared with the referents. When adjusted for age, heredity, shift work, educational level, marital status, and working class, the odds ratio was 2.34 (95% confidence interval 1.70-3.21).