The first season of Degrassi High premiered on November 6, 1989 with 15 episodes. It portrays the 1990-1991 school year.
- David Armin-Parcells as Claude Tanner, an 'environmental activist' and goth kid poseur, Caitlin's new love interest.
- Neil Hope as Derek "Wheels" Wheeler, a troubled orphan, plays bass in the band Zit Remedy.
- Stefan Brogren as Archibald "Snake" Simpson, a tall, friendly student, plays guitar in the band Zit Remedy.
- Anais Granofsky as Lucy Fernandez, a worldly, popular girl with neglectful parents who is starting to take an interest in filmmaking.
- Amanda Cook as Lorraine "L.D." Delacorte, an athletic tomboy and feminist secretly battling leukemia.
- Angela Deiseach as Erica Farrell, a loud, boy crazy girl who has a love/hate relationship with her twin sister, which reaches a breaking point when a summer fling gets her pregnant and she has an abortion.
- Maureen Deiseach as Heather Farrell, a somewhat timid girl with strong religious beliefs who has a love/hate relationship with her twin sister.
- Amanda Stepto as Christine "Spike" Nelson, an easy-going, punk-rock girl who is dealing with being a unwed teen mother and trying to find love.
- Cathy Keenan as Liz O' Rourke, an opinionated, punk rock girl who creates conflict with her classmates with her strong beliefs on abortion and animal rights.
- Irene Courakos as Alexa Pappadopolos, an overly dramatic, boy-obsessed girl.
- Michael Carry as Simon Dexter, a cute, dim-witted student and Alexa's boyfriend, famous around school for his budding modeling/acting career.
- Maureen McKay as Michelle Accette, a shy girl from a broken home now struggling to live on her own, Alexa's close friend.
- Dayo Ade as B.L.T. Thomas, an athletic student and talented basketball player, Michelle's supportive boyfriend.
- Sara Holmes and Jacy Hunter as Amy Holmes and Alison Hunter, inseparable best friends, stuck up and snobby troublemakers.
- Pat Mastroianni as Joey Jeremiah, a humorous and immature class clown dealing with a learning disability, plays keyboard in the band Zit Remedy.
- Stacie Mistysyn as Caitlin Ryan, a human rights activist and aspiring journalist who gets into trouble with the law when she takes her activism to the next level.
- Kyra Levy as Maya Goldberg, a Jewish girl in a wheelchair, Caitlin's close friend.
- Sara Ballingall as Melanie Brodie, a gawky but open-minded girl always trying to 'fit in'.
- Rebecca Haines as Kathleen Mead, a gossipy girl with a bad attitude who falls into a physically abusive relationship with an older boy.
- Chrissa Erodotou as Diana Economopoulos, a boy-crazy, chain-smoking girl with strict Greek parents.
- Duncan Waugh as Arthur Kobalewscuy, an awkward, newly wealthy outcast struggling with losing his best friend to a 'cool' new crowd.
- Siluck Saysanasy as Yick Yu, a former nerd who has beginning to re-invent himself, falling in with a 'cooler' crowd.
- Christopher Charlesworth as Scooter Webster, a short 'advanced development' geek making first attempts at dating girls.
- Trevor Cummings as Bartholomew Bond, a smart, snobby pipsqueak, Scooter's close friend.
- Kirsten Bourne as Tessa Campanelli, a hyperactive, immature girl just discovering boys.
- Adam David as Mr. Walfish, the 'hip' English teacher, generally seen teaching grade 10.
- John Weir as Mr. Webster, the Scottish science teacher, generally seen teaching grade 9.
- Dan Woods as Daniel Raditch, former junior high teacher, now the school vice principal.
- Michelle Goodeve as Karen Avery, former junior high teacher, now the school librarian.
- Steve Bedernjak as Clutch, a older, hard drinking, troublemaking student, Lucy's on-again off-again boyfriend. (Grade 12)
- Vincent Walsh as Patrick, an Irish punk rocker and Spike's love interest. (Grade 11)
- Byrd Dickens as Scott Smith, Kathleen's physically abusive boyfriend. (Grade 11)
- Darrin Brown as Dwayne Myers, the school bully who carries out 'initiations' on the new students to Degrassi, Joey's nemesis. (Grade 10)
- George Chaker and Michelle Johnson-Murray as Nick and Tabi, school bullies and Dwayne's partners-in-crime. (Grade 10)
- Arlene Lott as Nancy Kramer, a know-it-all, active student who keeps herself updated on everything. (Grade 10)
- Keith White as Tim O'Connor, a smart, bookish student, Nancy's best friend. (Grade 10)
- Andy Chambers as Luke Matthews, a troublemaking student involved in drugs. (Grade 9)
- John Ioannou as Alex Yankou, the school's biggest nerd. (Grade 9)
- Danah-Jean Brown as Trish Skye, a quiet red-headed girl, active in many school activities. (Grade 9)
- Tammy Campbell as Trudi Owens, a punk rock student with a bright red streak in her hair. (Grade 9)
- Annabelle Wough as Dorothy, Arthur's geeky cousin. (Grade 9)
- Ashlee Henricks as Emma Nelson, Spike's daughter.
- Bronco Davis (L. Dean Ifill) and Joanne Rutherford (Krista Houston) appear as background students in several episodes.
Main article: Episode Guide
|Season #||Series #||Title||Original Airdate||Production Code|
|1||1||"A New Start" Part 1||November 6, 1989||101|
|2||2||"A New Start" Part 2||November 6, 1989||102|
|3||3||"Breaking Up is Hard to Do"||November 13, 1989||103|
|4||4||"Dream On"||November 20, 1989||104|
|5||5||"Everybody Wants Something"||November 27, 1989||105|
|6||6||"Nobody's Perfect"||December 5, 1989||106|
|7||7||"Just Friends"||December 12, 1989||107|
|8||8||"Little White Lies"||December 19, 1989||108|
|9||9||"Sixteen" Part 1||January 9, 1990||109|
|10||10||"Sixteen" Part 2||January 9, 1990||110|
|11||11||"All in a Good Cause"||January 16, 1990||111|
|12||12||"Natural Attraction"||January 23, 1990||112|
|13||13||"Testing One, Two, Three..."||January 30, 1990||113|
|14||14||"It Creeps!!"||February 6, 1990||114|
|15||15||"Stressed Out"||February 13, 1990||115|