10 of the 77 pairs had flawless rides in the first qualifying round. The two riders who were eliminated during the round automatically received a score 20 points higher than the highest other score and continued to compete in the second round.
Round 2
The second qualifying round was also the first team round. Only one pair continued to progress without any penalties, though 27 had 10 or fewer.
Round 3
The third individual qualifier was also the second team round. All athletes competed individually regardless of their team's qualification. 45 pairs advanced to the final round. Only three pairs from any single NOC could advance. This meant that all pairs through 51st place were qualified, as that was the lowest place that would allow for no less than 45 pairs to advance after teams that had four qualified pairs selected three of them. Since there was a tie for 51st place, a total of 46 pairs advanced.
Final round
Round A
was assessed her first penalties of the event in the fourth round. Unfortunately for her but fortunately for many of the other pairs, all the scores had reset after the third qualifying round.
Round B
The 18-way tie for twelfth-place resulted in 29 pairs advancing to the second round of the final. A jump-off was required to break the tie for the silver medal. Royal Kaliber, an American horse ridden by Chris Kappler, was injured during the jump-off and the pair halted. Despite the injury, they received bronze medals. Rodrigo Pessoa and his horse Baloubet du Rouet earned 4 penalties in the jump-off, completing the course in 49.42 seconds.
On 8 October 2004, the International Federation for Equestrian Sports announced that the A-samples from four Olympic horses had failed doping control, and the Equestrian Federation of Ireland said one of these was Cian O'Connor's horse, Waterford Crystal. The urine B-sample went missing en route to a testing laboratory, prompting a flurry of media interest. On 9 November, testing of the blood B-sample confirmed traces of fluphenazine and zuclopenthixol. On 27 March 2005, the FEI gave a ruling disqualifying O'Connor and banning him from competition for three months, while accepting his contention that the drugs were administered by a vet as part of a sedative for a leg injury and were not with intent to enhance performance. O'Connor decided not to appeal and began his suspension on 11 April 2005. He was formally stripped of his medal at the end of the appeal window, on 3 July 2005.
Revised medals
Rodrigo Pessoa was presented with his gold medal in August 2005 at a ceremony on Copacabana Beach. The revised medal positions are:
