Results of a prospective population study of a random sample of about 7,500 men aged 47-55 years at baseline and followed-up for 27 years are presented. All results are based upon the baseline examination. Among men who smoked 1-14 cigarettes/day there were more events of lung cancer, myocardial infarction, stroke and all-cause mortality than in any of the other smoking categories. More events of myocardial infarction, stroke and all-cause mortality were found among men with serum cholesterol 6.00-6.99 mmol/L than among men with 7.00-7.99 and > or = 8.00 mmol/L. Similarly, more untoward events occurred in men with systolic blood pressures 140-159 mm Hg than in groups with higher levels. These results are due to the relatively low excess risk having been found among many individuals, giving rise to large effects in the population. They underscore the importance of avoidance of smoking even among those smoking "moderately", and to reduce cholesterol and blood pressure levels even among those with only moderately elevated levels. Non-pharmacological measures are indicated to reduce these levels.