The Recess Gang is in science class where they witness the binary fission of a bacterium. Gus is horrified when he finds out that bacteria and germs are the same thing, and believes that all germs can cause decay and disease. Mikey begs to differ, saying that bacteria and germs are living creatures and even gives each germ an individual name. As Mikey is about to release the germs, Gretchen makes the problem worse by informing Gus that germs are everywhere, causing him to run out of the classroom in a panic.
In the boys' room, the paranoid Gus is shown cleaning himself. At Recess, he shows up wearing a biohazard suit protecting him from germs. T.J. now realizes that Gus is overreacting, as Gretchen tries to clear up a few misconceptions, before suddenly starting to feel ill; she has caught a cold. It concerns Gus who is convinced that the germs have made her sick.
Gus is wandering round the playground in his suit, spreading the word about germs and frightening the Ashleys, when Menlo arrives, agreeing to help Gus in his anti-germ campaign, and putting on his own biohazard suit.
Gus holds a meeting in the playground discussing the dangers of germs, which Mikey observes atop Old Rusty. With nearly all the students joining Gus' campaign, Mikey decides to speak out for germs, but is jeered at by the students. Soon enough, they are cleaning up the playground and wearing masks and surgical gloves, and a couple of tanker trucks arrive to disinfect the area of germs. Mikey decides to protest by holding up degermification, and refuses to budge. This only leads to a furious tussle between the two, which results in Mikey dropping his slide and breaking it. Believing that Gus killed the germs, Mikey becomes furious with him and the two start a big fight, which continues for some time until Gretchen arrives, having recovered from her cold.
Gretchen rekindles Gus and Mikey's friendship by saying that 1) they are both behaving ridiculously; 2) Gus was wrong to try to disinfect the world just on account of her having taken ill because germs are everywhere, and one must learn to live with them; 3) Mikey was wrong to act like germs are his pets because they are single-celled and therefore have no legs, eyes, or even brains; 4) germs are neither good nor bad and they are just a part of life; and 5) while germs did make her sick, germs also made her healthy again; specifically, antibiotics are germs that help the body fight illnesses. She then mentions some germs are for making medicine, yogurt, and (this is to Gus and Mikey's major enjoyment) cheese. Gus and Mikey both make up for earlier, and Gus happily re-opens the playground. The disinfectant crew then depart, and the gang plays ball.
- After "Good Ole T.J." (When Gretchen shows up late, Gus mentions that "she is never been absent." However, she was absent once in this episode; it is safe to assume that this episode takes place after "Good Ole T.J.")
- Animation/consistency error: While T.J. is looking into the microscope on the school desk, this school desk is floating in the air.
- Animation/continuity error: While T.J. is looking into the microscope, there are some other students behind him. Once Mikey grabs T.J. to look into it himself, the students behind them are missing.
- Animation/coloring error: When Gretchen takes the basketball and then starts sneezing, the interior of her mouth flashes white several times.
- Animation/consistency error: The first truck to enter the playground has only one wheel at rear. When the trucks leave the playground later, there are two wheels at rear. However, it is possible that they are different trucks.
- Animation/continuity error: After Gus causes Mikey to drop the slide with germs and Mikey accuses Gus of doing it on purpose, Mikey's feet disappear for a frame.
- This is the only episode where Mikey hits somebody on purpose.
- This episode marks the first time a member of the gang is shown sick from school for a majority of the episode, this one being Gretchen. T.J. was mentioned to be sick for a week at the beginning of "Economics of Recess", however, this was before the events of the episode.
- This episode shares the same title as an episode of Dinosaurs.
- This episode is similar to the Hey Arnold! episode, "Sid and Germs".and the Rugrats episode "Mr. Clean".
- T.J. Detweiler - Andrew Lawrence
- Vince LaSalle - Rickey D'Shon Collins
- Ashley Spinelli - Pamela Segall-Adlon
- Gretchen Grundler/Ashley Tomassian - Ashley Johnson
- Mikey Blumberg - Jason Davis
- Gus Griswald - Courtland Mead
- Miss Finster - April Winchell
- Ashley Armbruster/Kid #3/Kid #5 - Anndi McAfee
- Ashley Boulet - Francesca Smith
- Ashley Quinlan - Rachel Crane
- Hustler Kid - Michael Shulman
- Menlo - Blake Ewing
- Erwin Lawson - Erik von Detten
- Gordy - Sam Gifaldi
- Kid #1 - Klee Bragger
- Kid #2 - Kath Soucie
- Kid #4 - Justin Shenkarow
- Kid #6 - Aria Noelle Curzon
- Man - Gregg Berger