At the 2008 Summer Olympics in Beijing, McGrath qualified for his second Canadian squad, as a 32-year-old senior, in the men's cross-country race by receiving one of the nation's three available berths from the Canadian Cycling Association and the Union Cycliste Internationale, based on his best performance at the World Cup series, World Championships, and Mountain Biking World Series. McGrath could not match a stellar performance from Athens, as he suffered a tyre puncture and then had to ride the rim all the way around the tech zone in order to replace the flat tyre. Realizing that his new wheel contained a slow leak at the designated site, McGrath decided to end his course with only three laps left and a forty-fourth-place finish.