A strong-running player, who is comfortable on the wing or at centre, Andrew Trimble stepped up to the provincial stage with Ulster aged just 19.

But he did not come to prominence until the following season making his Ulster debut against Cardiff at the Arms Park in the first Celtic League match of the 2005-06 season. Despite having just eight Ulster appearances under his belt, he made his international debut for Ireland in November 2005, winning his first cap against Australia at Lansdowne Road and scoring a brace of tries against Romania the following week.

Trimble made the squad for Ireland's 2006 Six Nations Championship campaign, scoring his third Test try against France, and retained his place in the elite set-up for the 2007 Rugby World Cup. He started all of Ireland's Six Nations clashes in 2008 but required surgery for a groin complaint later that year which ruled him out of Ireland's summer tour. A loss of form meant he missed Ireland's Six Nations Grand Slam campaign in 2009 and his injury jinx struck again that year when he required an operation to remove a piece of chipped bone behind his right knee.

He returned to the international stage at the end of 2009, featuring as a replacement against Fiji, and a return to top form saw him reclaim a place in Ireland's starting line-up for their opening clash of the 2010 Six Nations, against Italy. He made just one further appearance in the remainder of the Championship, as a replacement in the win over England at Twickenham, before returning to his usual berth on the left wing for the summer Test against the All Blacks in New Plymouth. Trimble did not feature in Ireland's autumnal clash with the Springboks in Dublin but he was included in the subsequent games against Samoa and Argentina.

Despite reported interest from clubs overseas, it was announced in January that he had signed a new contract with the Irish Rugby Football Union (IRFU) which will see him to continue to ply his trade with Ulster up until the end of the 2012-13 season. He went to the World Cup with Ireland, starting one of their matches and coming off the bench in four. And he started all of Ireland's Six Nations matches.