This study examined the effects of a Supportive–Expressive group therapy intervention offered to lesbians with early stage breast cancer. Twenty lesbians diagnosed with breast cancer in the previous 12-months were recruited and assessed at baseline, and at 3, 6, and 12 months after the group intervention. During the 12-week intervention, group members focused on the problems of a new diagnosis, coping with the illness and treatment, mood changes, coping responses and self-efficacy, improving relationships with family, friends and physicians, the impact of the illness on life, pain and sleep, and changes in body image and sexuality. A within-subject slopes analysis was conducted on data collected for each woman over the first year. As predicted, women reported reduced emotional distress, intrusiveness, and avoidance, and improved coping. There were significant changes in their social support, but in the unexpected direction. Instrumental support and informational support declined. However, conflict in family relations also declined, while trends were found towards more cohesiveness and expressiveness. Participants reported less pain and better sleep. There were no changes in body image, sexuality, or attitudes toward health-care providers. These results suggest that Supportive/Expressive group intervention appears to be helpful for lesbians with breast cancer. Copyright © 2002 John Wiley & Sons, Ltd.