This longitudinal study was conducted among 102 women with non-metastasic breast cancer to identify the time evolution and prevalence of distress at specific times through diagnosis and treatment of disease: preliminary diagnosis, surgery, definitive diagnosis and chemotherapy. Additionally, the study aimed to examine the role of demographic, medical and psychosocial factors on distress. The results indicated that prevalence of distress was higher at initial diagnosis (25%) than the following time points (approximately 17%). The differences inter-individuals in the levels of distress were observed over the four assessments. No relation between distress and demographic and medical factors was found. However, psychosocial aspects were significant risk factors. Patterns of emotional suppression and specific coping responses like helplessness/hopelessness, anxious preoccupation, cognitive avoidance and fatalism were positively related to distress, whereas fighting spirit and perceived social support showed a protective role. Moreover, helplessness/hopelessness and anxious preoccupation jointly predicted 75% of cases and 98% non-cases of distress. Finally, a mediational model between emotional suppression and distress through helplessness/hopelessness was tested. Results support the necessity of routine distress screening all through the illness. Implications of data for psychosocial interventions with breast cancer patients are highlighted.