The negative influence of alcohol on the ability of drivers for safe driving of motor vehicles is generally known. In order to determine the relative risk of traffic accident (especially with life consequences) in drivers after alcohol intake in comparison with those who are sober, the occurrence of such drivers in a common traffic is necessary. The authors controlled at random order the presence of alcohol in breath of 6180 drivers of passenger cars in the year 2001. The examinations were negative in 5839 cases, 150 offences were executed at the spot (as the breath test indicated level below 0.3g/l), 36 drivers refused blood sampling, which on the other hand was made in 155 drivers. The concentration o 0.3g/l and more was established in 145 drivers, i.e. 2.35 % of all controlled individuals.

        Key words: alcohol – car driving ability – proportion of driver with alcohol in blood