The aim of this diploma thesis is to examine the factors affecting driving under the influence of alcohol of car drivers and motorcycles. To achieve this goal, the responses of a representative sample of Greek drivers of cars and motorcycles are examined from the pan-European research SARTRE 4 and are analyzed by the development of logistic regression models. The application of the models revealed that the factors affecting driving under the influence of alcohol are six for car drivers and seven for motorcyclists, four of which are common. The common parameters are: age, their opinion on whether most of their friends would be driving under the influence of alcohol, their opinion on whether a person is capable of driving carefully in case of consumption alcohol and their education level. Additional factors for car drivers are their view on the legal limit of alcohol consumption and their gender, and for motorcyclists it is their view on how dangerous driving under the influence of drugs is.