Robert De Niro as Leonard Lowe

Robin Williams as Malcolm Sayer

John Heard as Dr. Kaufman

Julie Kavner as Eleanor Costello

Penelope Ann Miller as Paula

Ruth Nelson as Mrs. Lowe

Max von Sydow as Peter Ingham

Anne Meara as Miriam

Dexter Gordon as Rolando

George Martin as Frank

Alice Drummond as Lucy Fishman

Richard Libertini as Sidney

Laura Esterman as Lolly

Barton Heyman as Bert

Judith Malina as Rose

Mary Alice as Nurse Margaret

Keith Diamond as Anthony

Bradley Whitford as Dr. Tyler

John Christopher Jones as Dr. Sullivan

Mary Catherine Wright as Nurse Beth

Jayne Haynes as Frances

Le Clanché du Rand as Magda

Yusef Bulos as Joseph

Steven Randazzo as Luis

Gloria Harper as Dottie

Gwyllum Evans as Desmond

Steve Vinovich as Ray

Tiger Haynes as Janitor

Harvey Miller as Hospital Director

Tanya Berezin as Psychiatrist

Peter Stormare as Neurochemist

Shane Fistell as Man in Hall

Waheedah Ahmad as Hysterical Woman

Charles Keating as Mr. Kean

Christina Huertes as Christina

Linda Burns as Fishsticks

Judy Jacksina as Hospital Receptionist

Gary Tacon as George

Rico Elias as Orderly #1

Mel Gorham as Nurse Sara

Chris Carolan as EEG Technician

Debra Kovner-Zaks as Cafeteria Nurse

Bret McCormick as Head Ward Orderly

Gordon Joseph Weiss as Ward #5 Patient

Byron Utley as Ward #5 Patient #2

Anthony McGowen as Ward #5 Patient #3

Paul Montgomery as Ward #5 Patient #4

Leonard Tepper as Ward #5 Patient #5

Vincent Pastore as Ward #5 Patient #6

Howard Feller as Ward #5 Patient #7

Libby Titus as Club Singer

Michael Hyde as Bus Driver

Tomislav Novakovic as Bartender

Adam Bryant as Librarian

Anthony J. Nici as Young Leonard

Oliver Block as Leonard's Friend #1

Buck Smith as Leonard's Friend #2

Joan E. MacIntosh as Teacher

Harry L. Seddon as Medical Student

Jack Mulcahy as Psych Ward Intern

Jason W. Fuchs as Pot-Head Hippie

Vin Diesel as Hospital Orderly (uncredited)