Who was the first doping case in Olympic track and field?

That was a Pentathlete, Hans-Gunnar Liljenwall, in Mexico City, in 1968. That case actually involved alcohol, not a performance-enhancing drug.

I consider the Pentathlon to be more or less a track-and-field event, but some people might not. If not, then Ben Johnson was really the first important track and field athlete to be disqualified for doping.

See the history, below:

https://en.wikipedia.org/wiki/Doping_at_the_Olympic_Games

The first official doping case for anabolic steroid use in the history of track & field at the Olympics happened in 1976.

As can be seen using the link in the first post, the first time testing was done for anabolic steroids was in 1976 (before that, the testing was looking at stimulants). A number of athletes tested positive, including Danuta Rosani, a Danish discus thrower who would have finished in 11th place had she not been disqualified.

https://en.wikipedia.org/wiki/Athletics_at_the_1976_Summer_Olympics_%E2%80%93_Women's_discus_throw

lanfranco I believe has the correct answer. To quote the Wikipedia article cited, the alcohol was consumed to "steady the nerves", which was considered to be "performance enhancing" and alcohol was a banned substance.

The first Olympic athlete to test positive for the use of performance-enhancing drugs was Hans-Gunnar Liljenwall, a Swedish pentathlete at the 1968 Summer Olympics, who lost his bronze medal for alcohol use, "two beers" to steady his nerves. Liljenwall was the only athlete to test positive for a banned substance at the 1968 Olympics, but as the technology and testing techniques improved, the number of athletes discovered to be chemically enhancing their performance increased as well.

https://en.wikipedia.org/wiki/Doping_at_the_Olympic_Games

I had wanted to stay out of this, but I can't. "Olympic track and field" is called "athletics" and is governed by the body currently known as World Athletics and formerly known as the International Amateur Athletics Federation. The modern pentathlon is NOT governed by World Athletics, so the answer to the question posed cannot be a pentathlete (sorry, Ianfranco and elburcher). As far as I can tell, the answer provided by looney_tunes -- Danuta Rosani of Poland, who was very unlucky to have been caught at the "steroid Olympics" in Montreal 1976 -- is the first person to have been involved in an Olympic doping case in "athletics", and so I voted for that response.

Liljenwall was indeed disqualified for doping, but, because it wasn't in a sport governed by World Athletics (the governing body for modern pentathlon is the Union Internationale de Pentathlon Moderne (UIPM)), he wouldn't be considered to be competing in Olympic track & field.

AyatollahK, what you said may be well and true, however the 1968 case is recognized as the first Olympic disqualification for performance enhancing drugs...

https://www.guinnessworldrecords.com/world-records/most-consecutive-opponents-squash-singles

The first official doping case in modern Olympic track and field (athletics) history was Polish discus thrower Danuta Rosani. During the 1976 Montreal Summer Olympics, which marked the very first time the International Olympic Committee (IOC) tested for anabolic steroids, Rosani qualified for the women's discus final. However, before she could compete, her drug test came back positive for an anabolic steroid. She was subsequently disqualified and removed from the Games. : While Rosani was the first inside track and field, the first overall athlete disqualified for doping under official testing was Swedish modern pentathlete Hans-Gunnar Liljenwall at the 1968 Mexico City Games. He was stripped of a bronze medal after testing positive for alcohol ("two beers" used to steady his nerves before the pistol shooting event). : Long before formal rules or testing protocols were introduced, American marathon runner Thomas Hicks famously collapsed after winning the 1904 St. Louis Olympic marathon. He had been openly administered a cocktail of brandy, egg whites, and strychnine (a stimulant in small doses) by his trainers mid-race. Because doping was not yet outlawed, he kept his gold medal. The 1988 Ben Johnson scandal in Seoul, which remains the most high-profile 100m sprint disqualification in Olympic history. How the World Anti-Doping Agency (WADA) was created in 1999 to standardize international testing. The evolution of drug testing technology, moving from simple stimulant checks in 1968 to advanced blood profiling.

elburcher, you're right that Liljenwall was the first disqualification for performance-enhancing drugs in the Olympics, and it would be the correct answer had the question posed been something similar to "What athlete was the first doping case in the Olympics?" But that wasn't the question posed; the question specifically asked about "Olympic track and field". So Liljenwall cannot be the correct answer, because Liljenwall was not competing in Olympic track and field.

The problem may be that Wikipedia called him a pentathlete. Should have called him a competitor in modern pentathlon. Modern pentathlon is not part of track and field.