All three medallists were previously banned for taking drugs, although James Doehring of America, who won the silver medal, had his two-year ban for using testosterone overturned after 18 months on a legal technicality, just before the US trials in June.
The winner, Doehring's compatriot Mike Stulce, returned to competition this year after a two- year ban; Vyacheslav Lykho of the Unified Team, the bronze-medallist, had his European bronze medal of two years ago taken away after he tested positive for stimulants. He served a three-month ban.
Stulce dominated the competition with four throws over 21 metres, the longest his fifth effort of 21.70 metres. Doehring, with 20.96, finished just two centimetres ahead of Lykho. The favourite, Switzerland's world champion Werner Gunthor, finished fourth with 20.91.
Stulce's winning throw was nearly 1.5m short of the Olympic record of 22.47, set by East Germany's Ulf Timmermann in Seoul four years ago, but the gold-silver finish by the Americans matched the that of Randy Matson and George Woods at the 1968 Mexico Olympics. Matson's gold medal that year was, surprisingly, the last in the shot put for the United States until yesterday.
Stulce said that he did not think the ban would devalue his gold medal. 'I've talked to several people who think I should be banned for life, but I have the proof I'm innocent,' he said.
Doehring, meanwhile, is still on five years' probation after being convicted in a San Diego court of illegal drug possession with intent to distribute.
Shot putting has been plagued with doping cases in recent years: Norway's Georg Andersen lost the silver medal he won at the world championships in Tokyo last year after a positive dope test.
As a footnote to yesterday's competition, 36-year-old Udo Beyer, the German Olympic champion in Montreal in 1976, retired after failing to reach the final.
Within 10 minutes of the finish of the shot put final, Barcelona- born Daniel Plaza won an emotional victory when he took the men's 20 kilometres walk in an unofficial 1hr 21min 45sec.
The 26-year-old Catalan, who was disqualified in last year's Tokyo world championships after finishing third, made no mistake this time, striding into the stadium to a thunderous ovation.
Canadian Guillaume Leblanc finished second and Italian Giovanni de Benedictis third. Spain may well have picked up another medal but Valentin Massana, who had been prominent in the leading bunch, was disqualified in the final stages.