Dexter's Laboratory Wiki
Changes "Changes" Premiere Order
"The Big Sister"
"Old Man Dexter" Old Man Dexter
Changes "Changes" Production Order
"The Big Sister"
"Old Man Dexter" Old Man Dexter
The Big Sister
Season 1, Episode 002/6c
Episode name reference to/pun on: Big sister, as in an older sister
The Big Sister
Air date March 10, 1996 (first airing)
June 1, 1996 (TNT; sneak preview; second airing)
June 2, 1996 (TBS and Cartoon Network; third airing)
Production number 002 (Pilot)
105c (Series)
Written by Genndy Tartakovsky
Storyboard by Mike Moon (Background Design)
Directed by Genndy Tartakovsky
Craig McCracken (Art Director)
Paul Rudish (Art Director)

The Big Sister is the second pilot of Dexter's Laboratory, which aired on March 10, 1996 on the What A Cartoon! series. It re-aired on June 2, 1996 as the third part of episode 6 in season one.

In this episode, Dexter is feeding experimental cookies to some of his lab rats to test them out. However, when Dee Dee eats one, she grows into a giantess and heads over to the city, making her think it's her own dollhouse. Dexter, using his mecha called the Robo-Dexo 2000, tries to revert Dee Dee to normal size.


While Dexter is inside his laboratory, he uses one of his machines to bake chocolate chip cookies. Just after he sets the plate of cookies on a pedestal, Dee Dee reaches for one of them and prepares to eat it until Dexter lunges at her and takes the cookie away. He explains to Dee Dee that the cookies are laced with formula X29 and are not meant for human consumption, as the cookies in question are for his lab rats. Dee Dee doesn't understand at first, but Dexter sternly tells her that she is not a rat and orders her to leave his laboratory. Later, Dexter tests his cookies on his lab rats and writes down the results on a clipboard. However, he inadvertently feeds one to Dee Dee, who is wearing a rat costume. As she dances around the laboratory, Dee Dee suddenly grows immensely and then heads to the city. Dexter, who is now relieved of Dee Dee's obnoxious behavior, goes back to work on his experiments. In the city, Dee Dee mistakes the citizens as dolls whereas the citizens all run in fear from her.

Dee Dee then plays cops and robbers using a real police car to jostle the man in his stomach. Back at home, Dexter is watching an educational science program on TV until it is interrupted with breaking news. While watching the President make his speech, Dexter starts to fantasize about receiving special recognition about ridding the world of the giant monster, ranging from him receiving the Brain of the Year award, getting a call from God, and receiving a kiss from Ms. Physics. He happily accepts to do it, then runs into his laboratory to suit up and pilot the Robo-Dexo 2000, his mech.

As Dexter prepares to take off with the Robo-Dexo 2000, Mom appears in front of his room door and he sends a robotic replica of himself in his place. As Mom leaves the robotic Dexter to play its game, she notices the plate of cookies on the pedestal. With everything settled, Dexter engages the Robo-Dexo 2000 and flies to the city. Meanwhile in the city, three tanks and a fighter jet are working to take down Dee Dee, who sneezes on the tanks after sniffing the fighter jet's exhaust. Dexter, in the Robo-Dexo 2000, lands behind Dee Dee and tells her it's time to go home with him.

Instead of complying, Dee Dee instead makes things hectic for her little brother as she knocks on the head of the Robo-Dexo 2000, giving it a wet willy, and body slamming it after she tells Dexter to catch her. Angered at her games, Dexter fights back by performing a high-flying kick. He misses, and Dee Dee gives him a kiss. Dexter then fires the Robo-Dexo 2000's missiles at Dee Dee, who gracefully dodges them and makes them hit the buildings behind her. Lastly, Dexter charges at Dee Dee, and she kicks the Robo-Dexo 2000 in the back of its head as she jumps up and spins around. Just after, Dexter is ejected from the Robo-Dexo 2000 when Dee Dee forcefully pushes it during a game of tag.

Dexter, who is now in the palm of Dee Dee's hand, begs for mercy as she undresses him. He quickly pulls out a cookie, to which Dee Dee eats. As she savors it, Dee Dee suddenly shrinks back down to normal size. Dexter breathes a sigh of relief. Suddenly, Mom, who is a giant cycloptic alien with wings, orders her children to clean up the mess. Dexter faints as Dee Dee continues to savor the cookie.

Voice Cast[]


  • Both this episode and "Changes" are the only two pilot episodes where Dad doesn't appear.
  • This episode marked the first appearance of Dexter's mechanical robot, the Robo-Dexo 2000.


  • While Dexter is talking to God, the sleeves of his white lab coat are missing.
  • The plate of cookies was first seen inside Dexter's laboratory, but later in the episode, the plate is in his bedroom.

Production Notes[]

  • This is the second of the pilot episodes.

Cultural references[]

  • The way Dee Dee grabs a man is a reference to the 1933 film King Kong.
  • The way the Robo-Dexo 2000 fires his fist rockets references the 1972 anime Mazinger Z.
  • As Mom enters Dexter's room to be greeted by a robotic replica of Dexter himself, a poster that references the Power Rangers can be seen on Dexter's wall.