Juan Martín Pereyra is an Argentine swimmer. He has represented Argentina at three consecutive Summer Olympics. At the 2004 Summer Olympics, he competed in the men's 200 metre freestyle, 400 metre freestyle and the 1500 metre freestyle, finishing in 40th, 27th and 26th respectively. At the 2008 and 2012 Summer Olympics, he competed in the 400 and 1500 metres. In 2008, he finished in 35th and 34th respectively, while in 2012 he finished in 24th and 29th.