Jack Lemmon as Harry Hinkle

Walter Matthau as Willie Gingrich

Ron Rich as Boom Boom Jackson

Judi West as Sandy Hinkle

Cliff Osmond as Purkey

Lurene Tuttle as Mother Hinkle

Harry Holcombe as O'Brien

Les Tremayne as Thompson

Marge Redmond as Charlotte Gingrich

Ann Shoemaker as Sister Veronica

Ned Glass as Doc Schindler

Archie Moore as Mr. Jackson

Howard McNear as Mr. Cimoli

Harry Davis as Dr. Krugman

Lauren Gilbert as Kincaid

Sig Ruman as Professor Winterhalter

Noam Pitlik as Max

Maryesther Denver as Nurse

Judy Pace as Elvira

Helen Kleeb as Law Firm Switchboard Operator and Receptionist

Bartlett Robinson as Specialist #1

Ben Wright as Doctor

Dodie Heath as Nun

William Christopher as Interne (as Bill Christopher)

Robert P. Lieb as Specialist #2

Martin Blaine as Specialist #3

Herbie Faye as Maury - the Equipment Man

Billy Beck as Maury's Assistant

Lisa Linsky as Ginger Gingrich (as Lisa Jill)

John Todd Roberts as Jeffrey Gingrich

Keith Jackson as CBS Football Announcer

Herbert Ellis as TV Director (as Herb Ellis)

Robert DoQui as Man in Bar (as Bob Doqui)

John Anderson as Abraham Lincoln (uncredited)

Jim Brown as Running Back - Number 32 (archive footage) (uncredited)

Daniel Elam as Bar Patron (uncredited)

Rudy Germane as Commuter (uncredited)

Chester Jones as Cook (uncredited)

Chuck Schodowski as Stadium Cameraman (uncredited)

Jon Silo as Tailor (uncredited)