Hoelzer, who was a key member of Auburn's 2004 NCAA Championship team as a junior All-American, swam a time of 2:11.88, the sixth fastest in the world this year, to finish ahead of runner-up Kristen Caverly, who was well back in 2:12.70.
Hoelzer becomes the fourth member of Auburn's national championship women's team to qualify for the 2004 Olympics. She joins Eileen Coparropa of Panama, Kirsty Coventry of Zimbabwe and Jana Kolukanova of Estonia as 2004 Auburn female swimming Olympians.
Hoelzer is one of three Tigers who will represent the U.S. at the pool in Athens along with Mark Gangloff, who qualified in the men's 100-meter breaststroke, and Caesar Garcia, who won the platform event at the diving trials.
Margaret Hoelzer came to AU from Huntsville High School.
Hoelzer won the NCAA 200-meter freestyle earlier this year and was second in the 200-meter backstroke and the 100-meter backstroke. In 2003 she won the silver medal in the 200-meter backstroke at the FINA World Championships and a gold medal for the U.S. 800-meter freestyle relay.
Another Auburn swimmer, Erin Volcan, finished sixth in the 200-meter backstroke on Tuesday night. Only the top two competitors in the event qualified for the U.S. Olympic team.
Auburn's Hayley Peirsol reached the finals of the 800-meter freestyle on Tuesday and finished fifth in a time of 8:31.29. Diana Munz won the event with time of 8:26.06 and was followed by Kalyn Keller (8:26.33).
A pair of members from the national championship Auburn men's swimming team made the finals of the 50-meter freestyle. However, neither qualified with Ryan Wochomurka taking seventh with a time of 22.78 and Aaron Ciarla eighth 23.05. Gary Hall Jr. won the event with a 21.91 while 100-meter champion Jason Lezak was second at 22.05.
In the women's 50-meter freestyle on Tuesday night, Auburn's Becky Short swam a time of 25.57, which placed her ninth in the semi-finals. Jenny Thompson was the top qualifier with a 25.11.