This paper reported a preliminary study on Mat Rempit's activities and illegal motorcycle racing. Mat Rempit activities are becoming very popular among teenagers especially in major cities and towns in Malaysia. This phenomenon has created a new sub-culture amongst Malaysian teenagers. This study focused on psycho-social factors that encourage teenagers to involve in illegal motorcycle racing and to survey racing backgrounds (eg. racing types, time, places, prizes, etc.). Data was obtained through interview and live observations at the racing scene. One hundred racers and ex-racers had cooperated as respondents to feed this research with information. Results showed that Malay teenagers between 17-22 years old are the most involved in this activities. Also, moderating factors have been identified which are psychological factors where neurotic and extrovert personality traits and high level of self-esteem are found to correlate with racing involvement. Meanwhile, sociological factors such as peers, greatness flaunting culture and prizes are encouraging teenagers' involvement in illegal racing activities. Family and community roles to curb these unhealthy activities are suggested.