Jonathan Michael Petrie scored his first try for Scotland in the 31-8 win against Samoa in November 2000. Earlier in the year he won his first cap for Scotland in the second Test on the tour of New Zealand. In all, he played in five games on that tour, scoring a try in the 25-25 draw with Nelson Bays.
Jon was also on Scotland's 2002 North American tour, when he played in the Test against Canada in Vancouver, but concussion denied him selection against the United States. The 2000 tour to New Zealand was reward for his first season in professional rugby with Glasgow Caledonians (now Glasgow Rugby), during which he also made three appearances for Scotland A, making his debut in the 99-0 win over the Netherlands at Murrayfield in December 1999. He had two seasons in Scotland's under-21 team, making his debut against the Irish in 1997 while he was playing in France with Colomiers.
Jon returned to Dundee High School FP later that year, and he enlisted with Glasgow Caledonians in season 1999-2000, though he had already made emergency appearances for the professional team in 1998-99.