Since then he's racked up 38 tries and has cemented his reputation as one of the most dazzling and feared centres in world rugby.
He captained Ireland for the first time against Australia in November 2002 whilst winning his 31st cap and took over as skipper of the squad for the 2004 Six Nations after Keith Wood's retirement.
O'Driscoll has also played six test matches for the British and Irish Lions, and captained the tourists on the 2005 tour to New Zealand. Unfortunately his time on the pitch was painfully cut short when he suffered a dislocated shoulder in the 1st Test defeat to the All Blacks. This was thanks to a controversial "spear" tackle from All Blacks Tana Umaga and Keven Mealamu which ruled him out for the rest of the tour.
BOD returned from New Zealand, recovered, and signed a contract to keep him at Leinster until 2011.
In 2007 Brian led Ireland to their third Triple Crown in four years and was named player of the Six Nations in both 2006 and 2007.
Last year he skippered Ireland to their first Six Nations (and indeed Five Nations) Grand Slam in 61 years, and helped Leinster lift their first Heineken Cup.
Not bad, and there's no signs of him stopping yet.
Congratulations on your 100th Ireland cap Brian!
Here's a video of some of your best bits: