European 100 metre champion Dwain Chambers of Britain was the first to fall to a retroactive test for the new designer drug THG or tetrahydrogestrinone.
He was followed by four Americans: Shot-putter Kevin Toth, hammer throwers Melissa Price and John McEwen and finally, after months of legal wrangling, veteran middle-distance runner Regina Jacobs.
Calvin Harrison was suspended for two years for a second doping violation on Monday, rendering him ineligible for the Athens Olympics.
The US Anti-Doping Agency said that Harrison was found guilty of using the stimulant modafinil at the U.S. track and field championships in June 2003. His case was heard last week by a three-member arbitration panel, which rejected Harrison's appeal of the test results.
Modafinil is a central nervous system stimulant that was prohibited at the time of the test because it is related to the classes of substances banned under IAAF rules.
Montgomery, along with sprinter Chryste Gaines and 400m runners Alvin Harrison and Michelle Collins went to the US trials having been notified by USADA that they faced lifetime bans based on evidence gathered in the BALCO case.
Calvin Harrison, Alvin's twin brother and a 400m runner also, ran in the trials facing a ban after testing positive for the stimulant modafinil.
{{/usCountry}}Calvin Harrison, Alvin's twin brother and a 400m runner also, ran in the trials facing a ban after testing positive for the stimulant modafinil.
{{/usCountry}}Equestrian Meredith Michaels-Beerbaum was dropped from consideration for the German Olympic team after her horse, Shutterfly, tested positive for a tranquilliser.
Already a couple of weightlifters - Poland's Szymon Kolecki and China's Shang Schichun - have been thrown off their Olympic teams in the wake of positive tests.
Weightlifting and cycling - two sports with long histories of doping - sparked a drugs row that threw the Australian Olympic Committee's final preparations for Athens into disarray in July.
Weightlifter Caroline Pileggi lost a bid to be reinstated to the Aussie Olympic team, from which she was dropped for refusing to take a doping test.
But cyclist Sean Eadie was renominated for the team after drugs allegations against him were dismissed.