Chris Rock

Osmosis Jones (voice)

Laurence Fishburne

Thrax (voice)

David Hyde Pierce

Drix (voice)

Brandy Norwood

Leah (voice)

William Shatner

Mayor Phlegmming (voice)

Ron Howard

Tom Colonic (voice)

Kid Rock

Kidney Rock (voice)

Bill Murray

Frank Detorre

Molly Shannon

Mrs. Boyd

Chris Elliott

Bob

Elena Franklin

Shane Detorre

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)

Héctor Mercado

Additional Character Voices (voice)

Paul Pape

Male Red Blood Cell #2 (voice)

Marilyn Pasekoff

Additional Character Voices (voice)

Chris Phillips

Firefighter Doug (voice)

Lynne Redding

Additional Character Voices (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

Jack McCullough

Zookeeper

Will Dunn

Oyster Boy

Jackie Flynn

School Janitor

Kelsey Jordan

Bus Girl #1

Abe Farrelly

Bus Girl #2

Jesse Peter

Laughing Boy

John-Eliot Jordan

Pea Soup Manager

Nancy Byers

Pea Soup Supervisor

Kevin J. Flynn

Docky's Clamshack Waiter

Sean Gildea

Dreamy Photographer

Kathryn Frick

Nurse #1

Nikki Tyler-Flynn

Nurse #2

Elizabeth Jordan

Nurse #3

Zen Gesner

ER Doctor #1

Marc Hyman

ER Doctor #2

Zak Penn

ER Doctor #3

Diane Conrad

Zoo Visitor or Staff

Judith Conrad

Zoo Visitor or Staff

Thomas Jordan

The Zoo Visitor or Staff

Sydney J. Bartholomew Jr.

Zoo Visitor or Staff

Erica Johnson

Zoo Visitor or Staff

Bo Cleary

Pea Soup Staff

Bruce McIntyre

Pea Soup Staff

Colleen O'Donnell

Docky's Clamshack

Docky

The Bikini Gang

Joe Murphy

The Bikini Gang

Brian Mone

Police Officer

Sean Fitzgerald

Police Officer

Grace Costa

ER Nurse

Emily O’Donnell

School Girl