| Himself - Patient | played by Albert Alberti |
| Herself - Bone Marrow Transplant Unit | played by Adriana Malone |
| Herself - Medical Intensive Care Unit | played by Barbara Mann (II) |
| Herself - John's Wife | played by Debbie Moloney |
| Herself - Medical Intensive Care Unit | played by Judith Nelson (V) |
| Herself - Bone Marrow Transplant Unit | played by Keren Osman |
| Herself - Robert's Wife | played by Julia Romero (II) |
| Herself - Marthe's Daughter | played by Sherley Schwartz |
| Herself - Bone Marrow Transplant Unit | played by Eileen Scigliano |
| Herself - Norman's Girlfriend | played by Kyimar Thein |
| Herself - Norman's Sister and Health Care Proxy | played by Phyllis Hunte |
| Herself - Bone Marrow Transplant Unit | played by Celia Grosskreutz |
| Himself - Professor of Medicine | played by Jerome Groopman |
| Harvard University | played by Jerome Groopman |
| Himself - Medical Intensive Care Unit | played by Scott Lorin |
| Himself - Narrator | played by Will Lyman |
| Himself - Patient | played by John Moloney (VIII) |
| Himself - Dean of Medical Education | played by David Muller (VIII) |
| Mount Sinai | played by David Muller (VIII) |
| Himself - Patient | played by Norman Smellie |
| Herself - Albert's Wife | played by Deborah Alberti |
| Herself - Marthe's Daughter | played by Nadege Viruet |