Traffic injuries are judged to be a public health issue worldwide. Risk-taking in traffic is influenced in combination by several behavioural, personality-related, and biological risk factors. The study focuses on the risk-taking behaviour in traffic in schoolchildren and car drivers. Among personality measures this work focused on five factor personality construct that measures Neuroticism, Extraversion, Openness to Experience, Agreeableness, and Conscientiousness and on Adaptive and Maladaptive Impulsivity Scale that measures Thoughtlessness, Fast Decision Making, Disinhibition and Excitement Seeking. Associations between risk- taking behaviour in traffic and markers of risk- taking behaviour of the serotonergic system in the brain like platelet monoamine oxidase activity and serotonin transporter gene polymorphism have been shown in the work. If people with high traffic risk could be identified using markers of risk-taking behaviour, public health workers, traffic safety experts and politics could better target traffic injuries preventive programmes and they would be more effective.