A Mat Rempit is a Malaysian term for "an individual who participates in illegal street racing", usually involving underbone motorcycles, colloquially known as Kapcai, or scooters. Not all Mat Rempits are involved in street racing; some of them perform stunts for fun, such as the wheelie, superman (lying flat on the seat), wikang, and scorpion (standing on the seat with one leg during a wheelie).
Mat Rempits usually travel in groups and race in bustling city centres on weekend nights. In recent times, Mat Rempits have been linked to gangsterism, gang robbery, street fighting, assault, vandalism, theft and bullying. Most motorcycles used by the Mat Rempits do not meet standard specifications, or have been modified extensively for greater speed, or just to make the exhaust noisier.
According to Selangor police chief Datuk Tun Hisan Tun Hamzah, it was the parents who are the ones who should be blamed on this and while Kuala Lumpur deputy police chief, Datuk Amar Singh said that it was due to lack of parents' attention, Amar also pointed out that especially when they are in a big group, they would act beyond the limit by attacking the authorities and challenging traffic laws indiscriminately, further pointed out that their peers will challenge them to do something outrageous like assaulting police officers and challenging road rules, just to prove that they're not cowards." 
Additionally, some Mat Rempits do not have valid motorcycle licenses, do not pay road taxes, and ride stolen motorcycles. A growing number of housing estates have also been turned into racing tracks. It is estimated that there are about 200,000 Mat Rempits in Malaysia.
In some other countries, the term Mat Rempit is also used, but more to refer to one as a motorcycle lover or rider (Mat Motor), as opposed to an illegal motorcycle racer. Sometimes, the term "Mat Rempit" is misused to refer to any individual who rides an underbone motorcycle. Related to this is the Mat Konvoi, which claim to be the non-racing version of Mat Rempit.
The word "Rempit" comes from "ram(rev)-it" (ram the throttle). According to Kamus Dewan, the definition of "Rempit" is "the act of whipping with a cane". An alternative source of the word is derived from the noise made by a 2-stroke motorcycle. "Mat" is a Malay slang term used to address or to refer to a male person who is usually of Malay descent but is generally used derogatorily.
In April 2009, Malaysia's Inspector-General of Police Tan Sri Musa Hassan said that the Mat Rempit had become violent and brazen instead of just being a public nuisance. He said "We have to come down hard on the Mat Rempit who have started to become involved in robberies, snatch thefts and are even attacking innocent road users and we also need to use harsh tactics to catch the Mat Rempit that try to runaway from the roadblocks ." He also added that "Parents must be more responsible and should not allow their underage children to drive cars or ride motorcycles"
Mat Rempits often end up being hospitalised after they fail to perform their actions or stunts such as 'superman', 'spider' and many more. Every weekend, around 10 people are hospitalised after being involved in accidents when riding motorcycles at high speed.
There are numbers of political influence in helping Mat Rempit.
Khairy Jamaluddin and Abdul Azeez Abdul Rahim from Putera ". Khairypits" should become the "Eyes and Ears" of Malaysian
Adopt Mat Rempit
Kelantan to build track for Mat Rempit
Kosmo! reported that Mat Rempit in the state of Kelantan will be allowed to show off their skills at a special track to be built by the state government soon. The Menteri Besar of the state of Kelantan, Datuk Nik Abdul Aziz Nik Mat said the track in Tanah Merah was not a waste of money.
|“||They (Mat Rempit) always make their mothers and wives worry. With the track they will have a proper place to express their feelings and show their bravery and heroics||”|
Kedah considering circuit for Mat Rempit to race
The Government of the state of Kedah is looking into the possibility of building a circuit  for Mat Rempit to race and overcome the menace, saying another option was to create more job opportunities for them as most of them were jobless. Azizan said:
|“||We will first study if the circuit in Kelantan has effectively curbed the menace||”|
Notable massive operations
On 3 May 2009, the Bukit Aman Traffic Division of the Royal Malaysian Police, together with the Road Transport Department, have launched a major integrated operation to crack down on both car and Mat Rempit motorcycle illegal racing. More than 115 motorcycles were impounded in the major operation which was held simultaneously in Kuala Lumpur, Selangor, Penang and Negeri Sembilan.
Mat Rempit is the focus of several Malaysian films:
- GILA – GILA REMAJA (1984)
- ALI SETAN (1985)
- LITAR KASIH (1996)
- KL MENJERIT (2002)
- KL MENJERIT 1 (prequel of KL Menjerit; 2005)
- REMP-IT (2006)
- Bohsia: Jangan Pilih Jalan Hitam (2009)
- Adnan Sempit (2010)
- V3 Samseng Jalanan (2010)
Songs aiming Mat Rempits
- Kazar – Memburu Impian (from Gila-Gila Remaja)
- Spider – Salut (From Bintang 12)
- Namewee – Kawanku
- Yazer featuring Doul – Rempit
- Ustaz Akhil Hayy Rawa – Relaku Rempit (parodying Spider's song called Relaku Pujuk)
- JJ and Rudy (The Morning Crew) from hitz.fm – Not So Furious (parodying Teriyaki Boyz's called Tokyo Drift)
- Fairuz Hafeez – Kisah Mat Rempit / Mat Rempit Jatuh Tergolek
Mat Rempit was also the main influence for the song "Salut" by the Malaysian band, Spider, in their album Bintang 12
- Street racing
- Kapcai, Mat Rempit's common bike types
- Bōsōzoku: Mat Rempit's origin, and Japanese counterpart
- List of subcultures
- Ah Beng: the Chinese counterpart to the Mat Rempit, who sometimes drives a bespoilered hot hatch.
- "Young, fast, and safe", The Sun (Malaysia), 6 May 2014
- Motorcycle gang robs vendor of RM70
- Mat Rempit gang menace Rep: Three robberies brought to my attention
-  Archived 13 November 2008 at the Wayback Machine
- [dead link]
- Mat Rempit[dead link] The Star Online Motoring Blog
- Membendung lumba haram Harian Metro Archived 10 February 2007 at the Wayback Machine
- Residents fed up with Mat Rempit ruckus go after them
- Rempit – Budaya Menunjuk-nunjuk – Kosmo! (4 January 2007)
- Rujukan Kamus Terbitan DBP[dead link]. (Malay) Retrieved on 28 January 2010
- kennysia.com: Adopt-A-Rempit
- Archives | The Star Online
- Archives | The Star Online
- "115 motor kena angkut (Malay)", Harian Metro, 4 May 2009
- Illegal racers and spectators to face heavier fines and longer jail terms
- Mat Rempit re-branding futile
- Mat Rempit ‘untameable’
- Mat Rempit beat up executive
- Remp-It film