Psychodynamic psychotherapy is effective as an approach to understanding the psychological conflicts and the psychiatric symptoms of cancer patients as well as to planning useful psychological interventions. The author recommends that the psychotherapist who treats cancer patients be familiar with the following: 1) the natural course and treatment of the illness, 2) a flexible approach in accord with the medical status of the patient, 3) a common sense approach to defenses, 4) a concern with quality-of-life issues, and 5) counter-transference issues as they relate to the treatment of very sick patients. Case reports illustrate the unique problems facing psychotherapists who are treating cancer patients. Further, these cases show the effective use of psychodynamic principles to inform the therapist of successful psychotherapeutic interventions.