19 user 6 critic

The Immunity Syndrome 

The Enterprise encounters a gigantic energy draining space organism that threatens the galaxy.


Joseph Pevney


Gene Roddenberry (created by), Robert Sabaroff




Episode complete credited cast:
William Shatner ... Capt. Kirk
Leonard Nimoy ... Mr. Spock
DeForest Kelley ... Dr. McCoy
James Doohan ... Scott
Nichelle Nichols ... Uhura
Walter Koenig ... Chekov
John Winston John Winston ... Lt. Kyle
Majel Barrett ... Christine Chapel


The Enterprise is sent to investigate the disruption of the Gamma VII-A solar system and the destruction of the U.S.S. Intrepid, staffed solely by Vulcans. When they arrive they find a large dark mass floating in space that is draining energy from everything around it, including the Enterprise. Drawn into the mass, they find a huge amoeba-like creature and Kirk must decide which of his two friends, McCoy or Spock, to send into it aboard a shuttle craft on a mission of no return. Written by garykmcd

Plot Summary | Plot Synopsis


TV-PG | See all certifications »


Official Sites:

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Release Date:

19 January 1968 (USA) See more »

Company Credits

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Technical Specs


Sound Mix:




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Did You Know?


The equipment inside the shuttle craft included computer banks that were previously seen in the Starbase operations room in Star Trek: The Original Series: The Menagerie: Part I (1966) and the Eminian war room in Star Trek: The Original Series: A Taste of Armageddon (1967). See more »


When the Enterprise enters the body of the organism, there is a violent impact which knocks Uhura and her chair to the ground. The camera cuts briefly to the Enterprise inside the organism, and when it returns to the crew just a moment later, Uhura is still sitting in her upright chair as if it never fell over. See more »


Mr. Spock: Sir, we are accelerating. We're being pulled toward the center of the zone of darkness.
Capt. Kirk: By what, Spock?
Mr. Spock: Unknown, Captain. I suggest you order Mr. Scott to give us reverse power.
Capt. Kirk: He just gave us reverse power. We lurched forward.
Mr. Spock: In that case, Captain, I would suggest we apply forward thrust.
See more »

Alternate Versions

Special Enhanced version Digitally Remastered with new exterior shots and remade opening theme song See more »


Spoofed in XXX Trek: The Final Orgasm (1999) See more »

Frequently Asked Questions

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User Reviews

The Enterprise attacks a giant amoeba
29 December 2007 | by Guerticus_MaximusSee all my reviews

The Immunity Syndrome" feels like a first-season episode – not a lot of action, but plenty of drama. In most other TOS episodes, the villain is an alien race or some psychotic member of the Federation. In this episode, the villain is a giant amoeba. Not one of Trek's more memorable villains.

I hated this episode when I was a younger. Not enough action, no planet to visit, Klingons to fight or Trek babe to drool over. But it seems to grow on me as I get older. I can appreciate this episode for the drama and certainly don't consider it a stinker anymore. However, I wouldn't put in the top half of best Treks, though it's probably somewhere near the top of the bottom half.

I'm giving "The Immunity Syndrome" a C+ grade.

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