The purpose of this research was investigated the relationship between posttraumatic growth (PTG) and defense styles in cancer survivors. 95 patients suffering from cancer were selected. Participants completed posttraumatic growth inventory and defense style questionnaire. Data was analyzed using Pearson correlation coefficient and multi-variable regression. Results showed that there is a positive and significant relationship between PTG and mature defense style, and no relationship between PTG and neurotic and immature defense styles. Findings also showed that defense mechanisms of suppression and sense of humor have direct and projection has indirect relation with PTG. Defense styles and defense mechanisms in predicting PTG have a significant contribution, and defense mechanisms can predict the level of individual adaptation.