Driving ability of 34 males under minor influence of alcohol was tested at the ART 90 test unit of the Austrian Road Safety Board. Furthermore, 22 males not under the influence of alcohol, formed part of the sober control group. Some months previously, all volunteers had completed a driver aptitude test consisting of identical tests for all participants. Therefore a before-and-after analysis as well as a comparison of the different groups could be carried out by means of MANOVA. A high motivational level was guaranteed in the first tests as all test persons' driver qualification depended on the results of their driver aptitude tests. Months later they were invited to participate in this study on a voluntary basis. The second tests took place immediately after a social evening at which 8 volunteers were present at any one time. To create conditions as near to reality as possible, only alcohol that would be readily available to the public was served. An entertainer ensured an equally cheerful and relaxed atmosphere in both the experimental and control groups. Alcohol levels were measured by means of the Siemens breathalyser. Results show that as early as an average alcohol level of 0.67/1000 performance is significantly impaired: three times more errors in concentration tests, twice as many errors in reaction tests, twice as many observation errors in visual structuring and a considerable reduction of reactive stress tolerance. On the other hand quantitative dimensions of performance such as reaction time are not significantly impaired. In addition, the readiness to take risks increases with alcohol consumption as is shown by means of questionnaire.