This Diploma thesis aims to investigate the impact of level junctions in relation to other selected parameters, on the frequency and the severity of road accidents. On that purpose, especially processed data were used, extracted from the database of the Department of Transportation Planning and Engineering of the National Technical University of Athens (N.T.U.A.) for the time period 1996 – 2007 in Greece. Τwo sets of mathematical models were developed: twelve models with the use of lognormal regression method and six models with the general loglinear method with different accident severities in and out of junction. Using the lognormal analysis, the impact of the following parameters on the total number of accidents was examined: lighting conditions, weather conditions, accident type, vehicle maneuver, central barrier, ascent and descent. Using the general loglinear analysis, the lighting conditions, the weather conditions, the accident type, the central barrier and the level junction were examined. Analysis has led to a series of conclusions such as that the more usual accident type in junction is the collision at angle and that regardless of the area type, the accidents which occur out of junctions are at least double than those which occur at junctions.