Quintanilla made his debut for El Salvador, aged 16 years, in a February 2000 friendly match against Honduras and has, as of December 2011, earned a total of 59 caps, scoring 15 goals. He has represented his country in 19 FIFA World Cup qualification matches and played at the 2007 and 2009 UNCAF Nations Cups, as well as at the 2007, 2009 and 2011 CONCACAF Gold Cups.