Purpose: This study was to explore the psychosocial adjustment, marital intimacy and family support of post-mastectomy patients. Methods: The subjects were 90 post-mastectomy patients (stage I or II) who were eligible and agreed to participate in the study. The data collection period was from March to May, 2008. Subjects completed a survey including demographics, psychosocial adjustment scale by Lee (a 4-point Likert scale), marital intimacy scale by Kim (a 4-point Likert scale), and family support by Shim (a 5-point Likert scale). Data were analyzed using SAS (ver 9.0) program and frequency, mean (SD), t-test, ANOVA and Pearson correlation coefficients were used. Results: The mean scores of the psychosocial adjustment and marital intimacy were 2.8 (${pm}0.4$) and 2.5 (${pm}0.5$). Also, the mean score of the family support was 3.6 (${pm}0.7$). Regarding the correlation between the psychosocial adjustment, marital intimacy and family support, there was a positive correlation. Conclusion: These results showed that subjects who had higher marital intimacy and family support showed better in psychosocial adjustment. To improve psychosocial adjustment of post-mastectomy patients for breast cancer more effectively, there is an necessity to provide various strategic supports and intervention for effective communication with spouse and family.