Introduction. The risk of side effects secondary to global and non-specific immune suppression has limited the systematic application of immunosuppressive therapy in multiple sclerosis (MS). However, when a patient with MS develops a cancer, cytostatic drugs as treatment for the neoplastic process may induce improvement not only of the cancer but also of MS. Case reports. We present a series of four women with clinically defined MS and subiected to cytostatic therapy (cisplatin, 5-fluorouracil, leukovorin, adriamycin, tamoxifen and anastrozole) after the development of cancer: two presented breast cancer one colon cancer, and the fourth parotid gland malignancy Their clinical and neuroimaging course is described, following chemotherapy for the malignant disease. None of the patients have suffered further MS outbreaks. The four women have improved and remain clinically stable after neoplastic treatment. Magnetic resonance imaging showed persistence of the same lesion burden in three patients, and reduction in the other At the present one patient receives weekly intramuscular interferon-beta la, whereas the other did not received any treatment. Conclusions. Probably there are no specific cytostatics for MS. Immunosuppressive therapy could be a therapeutic option among patients with an aggressive clinical course. [REV NEUROL 2009; 48: 71-4]