Group psychotherapy has become an important modality of intervention in contemporary psychooncology. This article reviews and describes the rationale and foundations for group psychotherapy for women with metastatic breast cancer. It emerges from a replication study of an earlier study performed by Spiegel (Spiegel, Bloom, Kraemer & Gottheil, 1989), which demonstrated that participation in structured group psychotherapy resulted in improved psychosocial adjustment and a significant survival effect on women with metastatic breast cancer. Other intervention studies, psychosocial effects of psychosocial interventions, as well as psychosocial variables associated with the course of illness, are described. The contribution of existential considerations in psychotherapy is also articulated as a component of the group-supportive expressive intervention. Clinical illustrations, emerging from ongoing treatment groups, are used to demonstrate theoretical concepts.