The aim of the present study was to examine if coping strategies mediate dispositional optimism-posttraumatic growth relation in postoperative breast cancer patients. The data were collected from 90 patients in two hospitals. Regression analyses revealed that problem-focused coping fully mediated dispositional optimism-posttraumatic growth relation, but emotion-focused coping did not. That is, postoperative breast cancer patients who were optimistic were more likely to use problem-focused coping strategies that, in turn, led to the development of posttraumatic growth. The findings were congruent with the literature in which problem-focused coping was mostly highlighted as compared to emotion-focused coping, and in which optimism and problem-focused coping relationship was emphasized in the path of posttraumatic growth.