Protests against the Iraq war take place in over 600 cities worldwide. It is estimated that between eight million to 30 million people participate, making this the largest peace demonstration in history.

On 15 February 2003, a coordinated day of protests was held across the world in which people in more than 600 cities expressed opposition to the imminent Iraq War. It was part of a series of protests and political events that had begun in 2002 and continued as the invasion, war, and occupation took place. The day was described by social movement researchers as "the largest protest event in human history".According to BBC News, between six and ten million people took part in protests in up to sixty countries over the weekend of 15 and 16 February.The largest protests took place in Europe. The one in Rome involved around three million people, and is listed in the 2004 Guinness Book of World Records as the largest anti-war rally in history. Madrid hosted the second largest rally with more than 1.5 million people protesting the invasion of Iraq; Mainland China was the only major region not to see any protests on that day, but small demonstrations, attended mainly by foreign students, were seen later.