Marco Antonio Arriagada Quinchel (born October 30, 1975, in Curicó) is a Chilean professional racing cyclist. He is the brother of cyclist Marcelo Arriagada. He carried the flag for his native country at the opening ceremony of the 2007 Pan American Games in Rio de Janeiro, Brazil. After a very successful opening to his 2011 season, which saw him take victories in Argentina, Chile and the Dominican Republic, Arriagada tested positive for the anabolic steroid stanozolol during the Vuelta de Chile. He later received a four-year ban.