Each year from 1970 to 1975, selected sites within various municipalities representing all regions were utilized at least once on a weekend night by one of three research teams to take voluntary blood and breath tests for measurement of BAC levels from drivers of passenger cars. Data showed increasing drinking by drivers from 1970 to 1973. A more limited survey taken in 1974, aimed at studying the short-term effect of the new statutory BAC limit passed on November 1, 1974, showed that there was practically no drinking-driving during weekend nights. Although it is not possible to directly conclude how many accidents are alcohol-related, the different conditions after November 1, 1974 makes it probable that the reduction at night-time is due to the new legislation. The greatest part of this reduction occurs in the case of accidents involving moving passenger cars during weekend nights, which fell by about 100 during 1975 to slightly below 200. In spite of this, a year after the new law, drinking by drivers during weekend nights was still so high that supplementary measures become necessary to deal with the 1 in 10 driver who had a BAC higher than 100 mg/100 ml. Additional measures might include: (1) informing the police of the probable number of offenders based on the results of the roadside surveys, (2) improving screening facilities, (3) simplifying processing of the cases of drunken drivers, and 4) informing the public about police enforcement and the legal provisions of the drinking-driving laws. Eight tables and 10 figures are provided. (Author abstract modified)