List of terrorist incidents, 1991
The following is a timeline of acts and failed attempts that can be considered non-state terrorism in 1991.
- January 4: A criminal group attacks a Carabinieri patrol near San Lazzaro di Savena, Italy, killing 3 officers. 
- January 6: A bomb kills three and wounds seven in La Dorada, Caldas. No group claims responsibility.
- February 7: The IRA launched a mortar shell into the back garden of 10 Downing Street, London. (See 10 Downing Street#Security)
- February 16: The Medellín Cartel detonates a 440-pound car bomb near the Medellín bullring, killing 22 people, including 9 police officers.
- March 18: A car bomb blast in Antelias area, Beirut, Lebanon. No claim for responsibility in this blast, which killed eight people, injured 21 people, including Lebanese Defense Minister Michel Murr.
- May 13: Nine police officers die while deactivating a bomb left behind by leftist guerillas.
- May 21: Former Indian prime minister Rajiv Gandhi assassinated in a bomb blast believed to be the work of Sri Lankan Tamil terrorists belonging to the LTTE. This is also the first time that the suicide vest is used by any terrorist group.
- May 29: Basque ETA separatist group bombs the Guardia Civil police barracks in Vic (Barcelona), killing ten people.
- May 30: A train traveling from Moscow to Baku explodes near Karvin-Yurt station between Gudermes and Makhachkala in Dagestan, Russia. Eleven people die and eight are injured.
- July 12: Leftist groups bomb the runway at the Rafael Núñez International Airport in Cartagena.
- October 18: Two time bomb blast, when people watching a Hindu pagent of Ramila, Rudrapur, Uttar Pradesh, India, which blame on Sikh separatist militant. Killing at least 41 and injuring 140 people.
- November 15: Two IRA members were killed in St Albans when their bomb detonated prematurely. A civilian was also injured.