Objective: In this study, written educational materials related to breast cancer used for the education of patients were evaluated for their quality and suitability. Methods. In this descriptive study carried out between November 2010-March 2011, 17 examples of written educational materials used at 20 hospitals and outpatient clinics were evaluated using a Suitability of Written Materials form. Findings: It was determined that educational materials received average scores (12.5 +/- 5.4) for their suitability, 58.8% not being considered written at a readable level. Cultural suitability of the materials scored as 0.9 +/- 0.8, which was found to be moderate for Turkish population. Conclusions. Most of the written patient education materials used for patient education related to breast cancer need some modification in their literacy, plans and graphic parts. More materials related to care after mastectomy appear necessary. Future research needs to focus on patients' understanding of the content and their satisfaction with written educational materials.