Background: Breast cancer is the most common cancer in female population worldwide. In the psychological response to the disease some patients may develop Posttraumatic Stress Disorder (PTSD) symptomatology. The aim of this study was to examine the prevalence and structure of PTSD symptoms in Croatian patients following breast cancer and to identify some medical and psychological predictors of severity of these symptoms. Subjects and methods: 97 women, who were one month up to six years post-completion of all primary cancer therapy, participated in the study. The present research is cross-sectional with a mixed method approach. For the screening of PTSD symptoms PTSD Checklist - Civilian Version (Weathers et al. 1991) was used, with two open-ended questions added. Results: Using the cutoff method, 21.6 % participants met criteria for PTSD diagnosis. Qualitative analysis indicated future-oriented intrusive thoughts about reoccurrence of cancer, multidimensional nature of cancer as stressors, and hyperarousal symptoms related to internal stimuli. In hierarchical multiple regression analyses, identified predictors accounted for 35.2% of variability in PCL-C score. PTSD severity was predicted by stressfulness appraisal of the disease (β=0.45; p<0.001), external health locus of control (β=0.17; p<0.05) and self-appraisal of coping with cancer (β=-0.17; p<0.05). Participants who underwent radical mastectomy (M=44.41, SD=15.5) showed higher levels of PTSD than participants who had partial mastectomy (M=33.47, SD=13.68). Conclusion: Prevalence of PTSD symptoms obtained in this study should be considered as significant, taking into account the lifetime prevalence of PTSD in the general female population. Psychological assessment of women following breast cancer should more often include an assessment of posttraumatic stress reactions. Furthermore, results are in the line with issues of utilizing basic concept of PTSD in the oncology setting, and possible need of reconceptualization of cancer-related PTSD.