Great Britain and Northern Ireland (often referred to as Great Britain) is competing at the 2009 World Championships in Athletics from 15–23 August. UK Athletics announced a team of 60 athletes in July in preparation for the competition, although it was known that some athletes might not compete due to injury. Christine Ohuruogu entered the competition as the defending 400 metres champion. Selected athletes had achieved one of the competition's qualifying standards. Germaine Mason and Toby Sandeman withdrew from the squad due to injuries before the start of the competition.