In today's vehicles, active safety systems are introduced addressing a large variety of safety issues such as providing optimal stability control, braking effect, preventing spin and rollover, as well as collision avoidance, to mention just a few. In this study a literature review was performed in order to establish how the traffic safety performances of active safety systems with focus on Antilock Braking System (ABS) and Electronic Stability Control (ESC) are assessed. The areas covered were statistical evaluation, testing and driver behaviour. The literature review showed that in particular statistical methods, based on odds ratios, had been used in order to evaluate the traffic safety effect. In order to evaluate the effect of ESC in physical testing there are several test methods described in this report. Estimations of driver behaviour effects have been carried out by surveys among vehicle owners. Experiments performed in field or in simulator have also been found in the literature. From EU projects a variety of measures and test methods are available for assessment of driver behavioural effects.