A Diploma Thesis titled ‘Investigation of factors affecting helmet use among European motorcyclists‘ was presented by Christos Katrakazas in March 2013. Αn analysis took place, based on data from the SARTRE 4 Pan-European survey, which was conducted on a representative sample of European motorcycle drivers. Binary Logistic regression models were developed to investigate factors affecting helmet use on four types of roads (motorways, main roads between towns, country roads and built-up areas). These models were used on the samples from Greece, Europe as a whole, three groups of countries (Northwest, South and East) and three representative countries. According to the results from the models application, the main characteristic of the motorcyclists who are more likely to wear helmet, is that they fasten it frequently. On the contrary, the main factor that decreases the probability of a motorcyclist to wear helmet is helmet usage only because it is mandatory by law.