Ronaldo began his international career with the Portugal under-15's in 2001. In 2002, he played the U-17 Euro with Portugal's U-17. In June 2003, Ronaldo won the Toulon Tournament with the Portugal U-20. He played with the U21's in 2003 as well during the 2004 U-21 Euro qualification stages. He also played with the Portugal under-23 team at the 2004 Summer Olympics, where he scored one goal against Morocco. 