In Captain America: The First Avenger, we see that the Super Soldier Serum that created Captain America was destroyed when the Nazi spy blew up the lab, and its formula lost with his dead creator, just like in most other versions across all of Marvel.

In Captain America: Civil War, however;

The Winter Soldier was sent by Hydra to ambush Howard Stark's car in order to steal multiple vials of Super Soldier Serum so that more Winter Soldiers can be created.

It appears that the formula has been rediscovered. If that is so, why didn't the Americans produce more Captain Americas? That was the original plan back in World War II after all - they wanted an army, not just one Steve Rogers.

3 Answers 3


They've tried, repeatedly. But it isn't that simple.

First, and most importantly, it needs to be established that the Super Soldier serum has never been replicated properly. The closest anyone has come is the version that Arnim Zola used on James Buchanan "Bucky" Barnes, which seems to have bestowed the same endurance, strength and stamina on Bucky as it did Steve, but without the noticeable change in his body.

Other attempts include;

  • The experiment that turned Bruce Banner into Hulk (The Incredible Hulk)
  • The experiment that turned Emil Blonsky into Abomination (The Incredible Hulk)
  • The Extremis project (Iron Man 3)
  • The Centipede program (Agents of SHIELD)

These attempts all failed, for one reason or another.

Furthermore, it's worth noting that the version Howard Stark was working on wasn't great either.

Although it gave the recipients the strength, stamina, endurance etc that was expected, it also seemed to make them nigh on uncontrollable (at least at first), making them incredibly aggressive for seemingly no reason.

So in short, the reason that there aren't more super soldiers running around is because no one has the ability to truly replicate Erskine's original experiment.

  • 6
    @dasMetzger The explanation for the success of the experiment on Steve Rogers is simply that the process simply enhances what you already are. Erskine himself states that "good becomes great; bad becomes worse", which is his explanation for both how the Red Skull ended up the way he is, and why it was so important to make sure they person they chose is a good man. Commented May 18, 2016 at 12:32
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    So it's not a case of being able to replicate the serum... but in replicating Steve Rogers?
    – dasMetzger
    Commented May 18, 2016 at 12:34
  • 8
    @dasMetzger I think it's a bit of both. Sometimes, the method was wrong (Bruce Banner), but others, maybe it's just the wrong subject (Emil Blonsky). Captain America: Civil War states that the new Winter Soldiers were already highly feared before the experiments - maybe their aggression comes from the "bad becoming worse" rather than the Serum itself? Commented May 18, 2016 at 12:37
  • 8
    They always forget the Vita-Rays™
    – OrangeDog
    Commented May 18, 2016 at 12:53
  • 3
    @thegreatjedi The Serum used on Bucky was created by Zola, not Erskine. It's fair to assume that they weren't exactly the same formula, being as Erskine's was lost forever after the successful experiment on Steve Rogers. Commented May 18, 2016 at 13:08

In the MCU, the later attempts to recreate the supersoldier serum ended up creating the Hulk, as explained by Phil Coulson to Steve Rogers in The Avengers.

From imsdb


      Inside the QUINJET, Steve is sitting down, holding a TABLET,
      watching the footage of the Hulk's attack on the Army at Culver

       We're about forty minutes out from
       base, sir.
      Agent Coulson stands up from his seat and walks over to Steve.

       So, this Doctor Banner was trying to
       replicate the serum that was used on

       A lot of people were. You were the
       world's first superhero. Banner thought
       gamma radiation might hold the key to
       unlocking Erskine's original formula.
      The Hulk roars with fury as he slams a jeep apart.

So if it was rediscovered, it was certainly not by the US.


The US government successfully recreated the Super Soldier serum, but with limited success and ethical concerns.

The United States government did manage to recreate the Super Soldier serum after Steve Rogers' apparent death, but with mixed results and significant ethical issues. This story is explored in The Falcon and the Winter Soldier (2021), which reveals the controversial history of super soldier experiments in the US.

During the Cold War, the US military developed several versions of the serum and secretly tested them on African-American soldiers. These men were deceived into believing they were receiving tetanus shots. Out of all the experimental versions, only one proved successful: Isaiah Bradley.

Marvel Studios’ The Marvel Cinematic Universe: An Official Timeline

- Marvel Studios’ The Marvel Cinematic Universe: An Official Timeline

The series also introduces Dr. Wilfred Nagel, a former Hydra scientist recruited by the US government who successfully synthesized the serum using Isaiah Bradley's blood.

These vials were eventually stolen by the Flag Smashers, a group led by Karli Morgenthau, who used the serum to transform themselves into super soldiers. John Walker, who briefly held the title of Captain America, also obtained and used one of these vials, gaining super soldier abilities before becoming known as "U.S. Agent."

Marvel Studios’ The Marvel Cinematic Universe: An Official Timeline
Marvel Studios’ The Marvel Cinematic Universe: An Official Timeline

- Marvel Studios’ The Marvel Cinematic Universe: An Official Timeline

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