Chris Rock

Osmosis Jones (voice)

Laurence Fishburne

Thrax (voice)

David Hyde Pierce

Drix (voice)

Brandy Norwood

Leah (voice)

Elena Franklin

Shane Detorre

Bill Murray

Frank Detorre

William Shatner

Mayor Phlegmming (voice)

Ron Howard

Tom Colonic (voice)

Kid Rock

Kidney Rock (voice)

Molly Shannon

Mrs. Boyd

Chris Elliott

Bob

Jonathan Adams

Officer Tom (voice)

Carlos Alazraqui

Spanish Germ (voice)

Keith Anthony

Additional Character Voices (voice)

Eddie Barth

Conductor (voice)

Sally Brooks

Additional Character Voices (voice)

Rodger Bumpass

Joe Cramp / Announcer for Nerve News Network (voice)

Michael Carven

Additional Character Voices (voice)

Paul Christie

Dan Matter / Germ (voice)

Janis Dardaris

Additional Character Voices (voice)

Wendy Dillon

Additional Character Voices (voice)

Antonio Fargas

Chill the Flu Shot (voice)

Eddie Frierson

Frank Police Department Officer (voice)

Donald Fullilove

Doughnut (voice)

Jackie Gonneau

Additional Character Voices (voice)

Shannon Gregory

Additional Character Voices (voice)

Richard Steven Horvitz

Additional Character Voices (voice)

Rif Hutton

Charlie (voice)

Art Kimbro

Additional Character Voices (voice)

Joyce Kurtz

Additional Character Voices (voice)

Anne Lockhart

Female Red Blood Cell (voice)

Sherry Lynn

Trudy (voice)

Danny Mann

Musician Cell (voice)

Mickie McGowan

Brain Librarian (voice)

Kenny Olson

Kidney Rock Band (voice)

Jason Krause

Kidney Rock Band (voice)

Joe C.

Kidney Rock Band (voice)

Stefanie Eulinberg

Kidney Rock Band (voice)

Jimmie Bones

Kidney Rock Band (voice)

Uncle Kracker

Kidney Rock Band (voice)

Joel Silver

Police Chief (voice) (uncredited)

David Ossman

Scabies (voice) (uncredited)

John Melendez

Artie (voice)

Paul Pape

Male Red Blood Cell #2 (voice)

Marilyn Pasekoff

Additional Character Voices (voice)

Chris Phillips

Firefighter Doug (voice)

Al Rodrigo

Frank Police Department Walkie Talkie (voice)

Herschel Sparber

Bruiser (voice)

Doug Stone

Police Officer Jamie (voice)

Steve Susskind

Mob Boss Germ (voice)

Keri Tombazian

Additional Character Voices (voice)

Paul Tuerpe

Additional Character Voices (voice)

Robert Wisdom

Big Germ (voice)

Danny Murphy

Zookeeper Superintendent

Jackie Flynn

School Janitor

Abe Farrelly

Bus Girl #2

John-Eliot Jordan

Pea Soup Manager

Kevin J. Flynn

Docky's Clamshack Waiter

Sean Gildea

Dreamy Photographer

Kathryn Frick

Nurse #1

Zen Gesner

ER Doctor #1

Marc Hyman

ER Doctor #2

Zak Penn

ER Doctor #3

Thomas Jordan

The Zoo Visitor or Staff

Sydney J. Bartholomew Jr.

Zoo Visitor or Staff

Bo Cleary

Pea Soup Staff

Brian Mone

Police Officer