Breast cancer affects women physically and psychosocially. Protective factors such as social support are required when facing adversities affecting resilience, such as breast cancer. This study aimed to determine the level of resilience and social support among patients with breast cancer who underwent mastectomy. The descriptive and cross-sectional study was conducted with 176 breast cancer patients who underwent mastectomy in the general surgery clinics of two educational research hospitals. The data were collected before discharge using Patient Information Form, Connor-Davidson Resilience Scale 25, and Cancer Patient Social Support Scale. Descriptive statistics, independent sample t-test, one-way ANOVA and Spearman correlation analyses were used for data analysis. The mean score of resilience and social support were 72.56 ± 13.96, 149.59 ± 18.29 respectively, which were in the moderate range. Women with simple mastectomy had higher resilience scores than those with modified radical mastectomy (p <0.05). There was a positive relationship between resilience and social support scores (r = 369, p <0,001). In conclusion, the psychological resilience of women in the early postoperative period after mastectomy is positively related to social support. It is recommended that measure resilience and social support levels of patients who undergo mastectomy and plan nursing interventions to increase social support and improve resilience.