Men from the general population and male professional lorry and bus drivers were surveyed with regard to sleep habits and motor vehicle and other types of accidents. A random sample of 4000 men in the general population of Dalarna County in mid-Sweden were mailed a questionnaire and served as referents. A total of 1389 male professional lorry and bus drivers from this county responded to the same questionnaire. A total of 161 of the drivers also underwent a sleep study in their homes. The proportion of total accidents was higher among the professional drivers as compared with the males in the population, P=0.03. Reports on traffic accidents were the same in both groups, but the professional drivers reported more accidents at leisure compared with referents, P<0.0001. Accidents of any kind, traffic accidents included, among those affected by both snoring and apneas, were not reported more in either of the groups. At the sleep study, 17% of those examined received the diagnosis of obstructive sleep-apnea syndrome (OSAS). The professional drivers reported proportionally more sleep debt than the referents, P<0.001. Among referents, traffic accidents at leisure, traffic accidents while commuting and accidents at work increased in proportion to sleep debt (P<0.001, 0.006 and 0.002, respectively). The finding that self-perceived sleep debt may have an adverse effect on males in the general population and male professional drivers concerning accident likelihood should have an impact on prevention. These results stress the need to educate the general population on the importance of complying with our biological need of sleep.