The association between Rosai-Dorfman Disease (RDD) and cancer was reported for the first time in 1984. However, there are still a small number of reports of this association. We describe a 60-year-old woman who presented with a focal onset motor seizure followed by tonic-clonic generalization and persistent headache. Magnetic Resonance Imaging disclosed an irregular hyperintense lesion in T2 and vasogenic edema in the left parietal region. Immunohistochemical analysis of a biopsy fragment was positive for protein S-100 and CD68 and negative for CD1a, compatible with the diagnosis of RDD. She previously had breast cancer six years earlier and had used tamoxifen for two years and anostrozol for three years after diagnosis of cancer. RDD has been already associated with different cancers, such as Hodgkin's lymphoma, non-Hodgkin's lymphoma, follicular lymphoma, melanoma, adenocarcinoma and small cell lung cancer. As far as we know, this is the first report of an association between breast cancer and RDD.