Purpose: The purpose of this study was to examine stress, coping, and immune response effects of a psychosocial intervention program based on the PNI model and Stress-Appraisal-Coping for Korean patients with breast cancer. Methods: A nonequivalent control group pretest-posttest design was used. The participants who had survived breast cancer and lived in Wonju city and the surrounding area were assigned to an intervention group (N=21) or a control group(N=18).We conducted a 12-week intervention, 2 hours a day weekly, and measured the variables at baseline, six and twelve weeks later. Dependent variables are: stress, anxiety-depression and anger, and immune response. Results: Patients in the psychosocial intervention program reported significantly less stress perception (U=31.500, p=.023), more problem solving ability and less problem avoidance in coping (U=20.500, p= .013; U=29.500, p=.040), and less anxiety-depression (U=22.000, p=.023). No difference, however, was found in anger and. immune responses between the two groups. Intervention effects were evident at week 6 and 12 for anxiety-depression, and at week 6 for problem avoidance in coping, the same time that NK cell counts and the T8 decreased. Conclusions: These results suggested positive effects of a psychosocial intervention program. However, the results are inconclusive due to the small sample.