The 11 March 2004 Madrid train bombings (also known as 3/11 and in Spanish as 11-M) consisted of a series of coordinated bombings against the Cercanías (commuter train) system of Madrid, Spain on the morning of 11 March 2004 (three days before Spain's general elections), killing 191 people and wounding 1,800. The official investigation by the Spanish Judiciary determined the attacks were directed by a Muslim al-Qaeda-inspired terrorist cell although no direct al-Qaeda participation (only "inspiration") has been established. Spanish Muslims who did not carry out the attacks but who sold the explosives to the terrorists were also arrested.
Controversy regarding the handling and representation of the bombings by the government arose with Spain's two main political parties (PSOE and Partido Popular (PP)), accusing each other of concealing or distorting evidence for electoral reasons. The bombings occurred three days before general elections which resulted in the defeat of the incumbent José María Aznar's Partido Popular (PP), which had been enjoying a small and narrowing lead in the opinion polls. Immediately after the bombing leaders of the PP claimed evidence indicated the Basque ETA was responsible for the bombings, an outcome generally thought favorable to the PP's chances of being re-elected, while Islamist responsibility would have had the opposite effect, as it would have been perceived a consequence of the PP government's involvement in the Iraq War, a policy already extremely unpopular with Spaniards.
Nationwide demonstrations and protests followed the attacks. Some analysts claim that the Aznar administration lost the general elections as a result of the handling and representation of the terrorist attacks, rather than the bombings per se.
After 21 months of investigation, judge Juan del Olmo ruled Moroccan national Jamal Zougam guilty of physically carrying out the attack, ruling out any ETA intervention. The September 2007 sentence established no known mastermind nor direct al-Qaida link.