Audrey Hepburn as Sister Luke

Peter Finch as Dr. Fortunati

Edith Evans as Rev. Mother Emmanuel

Peggy Ashcroft as Mother Mathilde

Dean Jagger as Dr. Hubert Van Der Mal

Mildred Dunnock as Sister Margharita

Beatrice Straight as Mother Christophe

Patricia Collinge as Sister William

Rosalie Crutchley as Sister Eleanor

Ruth White as Mother Marcella

Barbara O'Neil as Mother Didyma

Margaret Phillips as Sister Pauline

Patricia Bosworth as Simone

Colleen Dewhurst as Dangerous Hospital Patient

Stephen Murray as Chaplain

Lionel Jeffries as Dr. Goovaerts

Niall MacGinnis as Father Vermeuhlen

Eva Kotthaus as Sister Marie

Molly Urquhart as Sister Augustine

Dorothy Alison as Sister Aurelie

Jeanette Sterke as Louise

Errol John as Illunga

Diana Lambert as Lisa

Orlando Martins as Kalulu

Penelope Horner as Jeanette Milonet (uncredited)

Charles Lamb as Pascin (uncredited)

Ave Ninchi as Sister Bernard (uncredited)

Richard O'Sullivan as Pierre (uncredited)

Frank Singuineau as Murderer of Sister Aurelie (uncredited)

Elsa Albani as (uncredited)

Gabriella Andreini as (uncredited)

Juan Aymerich as (uncredited)

Grazia De Rossi as (uncredited)

Giovanna Galletti as (uncredited)